What is my next step? I'm at a loss.

Long-distance caregiving adds to the stress and I'm sorry you are in this situation. In my experience the lies, exaggerations and stubbornness are probably your mom's dementia in action. She still has most of her abilities so that she recognizes she is now over her head and things are out of control but also has just enough cognitive problems and memory impairment to not be able to deal with any of it.

I have been in your shoes (and still am). There is a crisis coming very soon and you will need to decide what outcomes you are willing to live with. IMHO it would be "easier" to take 1 (preferably 2) weeks off to go there and get the "big" stuff done in person: get your parents to create their PoAs (before they can't), Advance Healthcare Directives, take them to their doctors to get cognitive/memory exams so that you know what you're dealing with, figure out their care going forward: contacting social services, visiting facilities, finding resources, talking to their neighbors, church, friends. Even if you don't anticipate being their primary caregiver or manager, it will be much more emotionally and mentally acceptable if you can get as much of this done as possible. I think when you go there you'll likely find a house in chaos, possibly unopened mail, unpaid bills, etc.

I'm not trying to add to your stress but just want to be honest that there *will* be a crisis that *will* require you to go there in person to pick up the pieces (if that's what you're willing to do). Go now on your terms, in your timing before the train comes completely off the tracks and then the crisis controls everyone. I strongly recommend 2 weeks (or more) as you will need to see doctors, lawyers, notaries, etc. and meet during week days. Also, I would carefully consider if you should tell her you're coming. I would have tempered expectations about her making any of the appointments herself. I'm hoping she won't be too resistant, but when you get there, give it a day or so before you start to move things forward. You will need to assess what's going on with them and how they are "managing" on a daily basis.

The hard truth is now you are probably driving the boat, not them (if you accept this role). If you choose to NOT step in (and this is not a judgment) then it is likely that those without a diagnosis of incapacity, with no PoA, will require "someone" to keep calling in APS until things get so bad that the county moves to acquire guardianship. When this happens, the county has all the control, permanently . They will most likely remove them to a facility that neither they nor you get to choose. You will have no insight into their medical or financial affairs any longer until they pass. I've been there, done this with a family member.

Or, you wait too long to intervene and neither parent is able to assign you as PoA and you must then go through the courts to acquire guardianship yourself -- an expensive and time-consuming process.

I'm just putting the realities out there so you can make as informed a decision as possible and are not "shell shocked" by what starts to come down the pike in the near future. It will feel overwhelming but you just eat the elephant one bite at a time. Get 1 thing done each day. Getting PoA would be the top priority right now if you wish to manage their care and make decisions for them.

For my own sanity I created a checklist that I give out to other family, friends and neighbors about where to start and what to do when one first attempts to help an LO in this situation. If interested, please just PM me. This is not a product for sale, I will email the pdf to you. May you gain wisdom and receive peace in your heart as you go on this journey with your parents.

When I ask my mother if she has enough Depends on hand, she tells me she has '4 million & can't possibly fit another into her small closet space.' In other words, she exaggerates to the point of flat-out lying. When I check her supply of Depends, they're down to one bag, if that. So I have to hustle to order more on Amazon so they arrive in short order.

Your mother running errands for '12 hours a day' sounds to me like one of my mother's infamous gross 'exaggerations'. Or a flat out lie, if you like. Trying to garner sympathy from you and/or elicit a panic reaction where you will drop everything and rush to her rescue so she can tell you to get lost, as she seems fond of doing.

You know the drill with your mother, right? If you stage an 'intervention', she'll likely throw a monkey wrench into it making it impossible for you to achieve one single good thing on her behalf. In situations such as this one you're facing, you'll likely have to wait for a crisis to happen before you can intervene to create a change. Since she refuses care, help, or anything else you offer, you can't force it upon her. SHE will have to ask YOU for what she wants or needs.

Trying to deal with this level of hostility is impossible, unfortunately. Just let your mother know that you are here for her, but that she needs to ask YOU for help. You're happy to set up online ordering services for her, or speak to her about end of life services, etc. Remind her that you're not the enemy here and for her to treat you as such defeats the purpose of you trying to help her out. It'll fall on deaf ears, most likely, but at least you'll have said YOUR peace.

I wonder if she's going down the dementia highway? Behavior such as she's exhibiting is common with dementia although not necessarily the only reason for it. Some elders are just mean.

I'm sorry you're going through such a stressful situation with your folks. Sending you a hug and a prayer that you can get through to her, some way, some how.

My Dad and his wife talk a couple times a week. Dad is here in Canada and Paddy is in NZ. For health related reasons they can no longer fly back and forth.

They do not tell each other the truth on how they are doing. Every couple months my sister in law and I have a chat and update each other on the reality of the situation.

So many care givers worry about using therapeutic fibs, our parents do it all the time.

They deny how bad things are getting, refuse help, and create a much greater problem than if they were upfront from the start.

Reading between the lines in your post.

If it took Mum 12 hours to run errands, or even all day, why? Did she get lost? Is she forgetful and has to go back to a shop? Is she no longer able to map out her travel to avoid back tracking? I know my former MIL could easily take an entire day if she had one doctor's appointment. Doctor, lab, pharmacy, lunch, spend 4 hours wondering through Walmart, snack, bank, pay bills, then home. We lived in a small town, so there was almost no travel time.

What can you do from a distance to help? Can you set her up for grocery delivery? What about a pharmacy that delivers? Online bill payments etc.

My Dad is a hoarder, which mean as well as collecting stuff, he never throws anything out. He does not clean his fridge, so there is no room for the fresh groceries etc. One year I was at my brother's house, pet sitting, and they and Dad (Dad lives in their suite) were at the family cabin. It was August, there was a bag of apples in Dad's fridge from the previous Fall. You can imagine how nasty 9/10 month old apples were.

Why did I mention Dad and his fridge, perhaps your mother did not have room in her fridge for the soup your had sent to her?

As others have said you need to arrange for a wellness check. If you know the names of their doctors, send them a letter outlining your concerns. Unless you are authorized via HIPPA rules or medical POA, they cannot talk to you, but your concerns will be noted. I did this with my MIL. We had the same GP. I told him about my concerns and said I understood that he could not talk to me about another patient.

Who has POA for finances and health for both your parents?

I think you should plan to make a trip to see your parents as soon as you are able. It sounds your Mom needs help now and is overcome and exhausted. Christmas is tough. It puts an onus and burden on people to "make nice" and "be happy". Clearly your Mom is too overwrought to keep up that pretense.
I would begin to think of how often you can touch bases with her.
Your parents are certainly too elderly now to travel to you. I know at 80 I find it increasingly difficult to go far distances. My daughter is only a few states away, short plane trip, and I can do it. But not easily.
You don't mention here how often you speak to your parents, and I mean just on a checking in basis, nothing to do with a holiday. If it is often you likely have a pretty good idea if Mom is OK overall or if she if crumbling under their needs versus their abilities. What she told you about what she is currently trying to do is quite overwhelming for an elderly woman, don't you think?
It does sound like your Mom may need to have help but that's almost impossible to discuss by video chat. I think if she has family in the area she is living it is time to check in with them. If you are the ONLY family, I think it is time to decide whether or not you are able to make a trip to assess the situation. If your elderly parents are alone they may be unable to maintain on their own without some placement or in home help for much longer.
I would take this video chat as a warning. Trouble is coming sooner rather than later would be my opinion. Your Mom is exhausted, and with exhaustion, Christmas soup is the last thing you want to discuss. She may even be sinking into depression. She sounds very hopeless.
I am so sorry. I know you are very far away. But try to think what you might do to help here. Getting actual made meals into the house will help more than a soup she has to make. I remember clearly when I understood my parents needed help with cleaning/housekeeping and they couldn't afford to get it, too afraid of digging into the nest egg. I was able to help then. My creaking old 80 year old knees NOW remind me of that time then................

After the holidays maybe call APS and ask for a well check. Just to make sure Dad is OK. They may offer them services they can use.