My Mom (92) refuses medical help. Her mind is deteriorating and she is combative. Any advice?

In the meantime while trying to do all the above advice, if your mom ever needs emergency help - and actually agrees to go to the ER - tell sis that this is the best time to step back. She can insist that they do an assessment/evaluation (if your mom is competent to take care of herself) while in the ER.

If sis still wants to caregive mom, then try to get meds to help your mother.

If sis no longer wants to caregive mom, and wants out, then she needs to harden her heart and tell the hospital that mom is not coming back home with her. They will do the guilt trip. She must be firm. This will then obligate the hospital to find a place for your mom -rehab, nursing home, etc... Whatever your sister decides, as siblings not doing the full-time caregiving, do Not make your sister feel she must do this. When I told my cousin that if dad ever calls the police accusing me of stealing from him, and I get arrested, then that is my last straw. I will pack up and leave. My cousin told me that it would be best for my dad if I stay to care for him...and not my other sibling who would dump dad at the facility,move into the house and make it their home. The guilt trip.... See?

Been there, done that. The worse they need care, the harder they resist. It’s fear and insecurity, and gets worse and worse with a lot of the dementias. But you & your sister have to take action anyway for her safety and wellbeing.
Any investigation into elder abuse would not just take the face value word of one person. My mom tried that trick while she lived with us for a short period, and I finally lost my cool one day over it. I told her a big fat lie. I said I’d been recording her in my house, in every room, and that I would hand over the tapes to the police so they could see who was really being abusive. That shut her up and she didn’t try it again. That’s when I knew the claim was 100% manipulation and not just crazy ranting by someone who didn’t know what they were saying.

My NC mom is as manipulative & ornery as they come, but I had to grab the bull by the horns and do what she needed, not what she wanted, like getting her to the doctor. Mom was combative, disoriented, confused, selfish, demanding, mean, abusive, etc. She could do very little for herself anymore living alone, but would not let anybody come in to help her except her brother in law & his wife. She was mean as a snake to them. Her house was almost ready for the TV show "Hoarders"...or the bulldozer.

You tell your mom whatever you need to, to get her to the doctor. You have special permission to say whatever will work. Tell her you're going for ice cream after you make this one stop over here.... Say you have to pop in to the office (don’t say doctor!) for something, and she has to come in with you because they all want to meet her. Say there's a new rule by the insurance company that she has to go in and be seen. It worked with my mom to say something vague like that and then claim ignorance of the details. I would just say that I'm doing what I was told to do. Mom already thought I was an idiot in the first place, so this was totally plausible. She also was not one to argue with authority figures too much to start with, so saying some government agency or office had said to go in went over MUCH easier than if I said that *I* wanted her to go in.

Ask yourself if you even need a rationale. Can you just work with your sister to get mom up, dressed enough, and into the car without a lot of talking & fuss? I think sometimes we project our own questions onto the person, and assume they need a logical explanation because we'd want one. Try just loading her up and going. You can say “we’re going out today mom”. Or “we won’t be out but for a short drive” or something reassuring but not revealing.

My mom is super volatile, and getting her placed in the right unit with the right anti-psychotics has made all the difference in her quality of life. It's so much better now than a year ago, when she was basically a raving lunatic shut in.
She's no sweet peach, but she's not drooling on her lap either. The right meds and the right environment can make a huge difference.

Does she receive any kind of check each month? Some have success saying that the government or insurance is requiring them to see the doctor for a routine check up so the checks can keep coming or that they need a new immunization shot. Anything to get them in the door.

There the doctor can ask a series of questions of her that will reveal mental and memory issues. You can step out and alert the doctor of your concerns. I actually wrote a list of my concerns that I slipped the doctor before she met with us, so she knew what I was dealing with.

It depends on how she would do mentally when talking with the doctor. Most of the nursing homes and/or Assisted Living facilities in NC, require that the doctor complete and sign something called an FL2 form. It's a state form and you can locate it online. The form allows the doctor what level of care she needs, such as assistance with bathing, dressing, walking, etc. Family members are actually the best source of this information, since she may not report things correctly.

If your mom is volatile, a doctor may likely suggest she go to a geriatric psychiatric wing or facility to have a mental evaluation as an inpatient, since she may need medication to get her stable enough to enter a long term care facility.
Paranoia, is very common with dementia patients. False reports are also quite common. Authorities deal with this and know how to sort through them.

Don't let Mom threaten because that can cause police trouble. You need to call her bluff by calling Adult Protective Services and getting a file going. Doctors can declare a person not capable of making medical decisions. Adult Protective Services can send evaluators out to the house to make a competency decision, at least in Florida. You may need to go to a lawyer to get a guardianship on her and then legally she has to do whatever you say. However, you may need to be less-than-upfront with her sometimes. Is there anybody she will listen to, like an old neighbor or church person? And you may want to consider a really frank talk with her about her wishes and her available options. Record it.

If she has not been found incompetent you may have to seek guardian ship. Can you get her to take a ride in the car? Can you make her a doc appointment and not tell her until you're there? In your sister's shoes, I would call aps and report that mom is claimong she's being held against her will and ask them to come out and do a wellness check. Maybe talking to a social worker will make a difference, maybe not. Sadly you may need to wait till she falls and have her transported to the er for treatment. Tell your sister that if that happens, she then works with discharge planning to get her into a good care situation.