Frustrating mother. Advice?

She doesn't remember what happens to the things you bring her because she has dementia. This woman CANNOT be allowed to continue living on her own.
The nonsense talk about the face cream turning her skin brown or about the bread is your mom trying to cover up her dementia. It's a type of showtiming.
I had a client with LBD who was declining. She was nice but I started to notice the covering-up behavior and didn't really know at first what it was. Like I'd come in and ask her what she wanted to do for lunch. She's always ask for her lunch favorites which were any kind of soup or French bread pizza. When the meal was in front of her she'd look at it for a minute then say she wasn't hungry or didn't like it. This was because she couldn't eat these foods on her own anymore and didn't want to have to be fed like an infant. So she was covering by claiming to not like the food or not be hungry. Your mother is doing the same thing. When I understood this, I stopped giving her foods she couldn't eat herself or adjusted some of her favorites so she could do it herself.
Your mother needs to not be living alone anymore. You have options and have to make a care decision before it's too late.

You mention in your profile that mom has Alzheimer's/dementia.
#1...Mom should NOT be living alone. Particularly if she is having the memory problems you indicate.
#2..You can not expect someone with dementia to "remember" that there are 2 loaves of bread, that she has face cream. You also can not expect her to remember to shut off the stove and not put a towel on a hot burner, you can not expect her to remember her way home should she decide to go for a walk or to get the mail.
#3..It sounds like you are not cut out to be a caregiver. Care manager maybe but not a caregiver.
You should be looking at either hiring round the clock caregivers for your mom or you should be looking for Memory Care places for her.
Staying at home, alone is not safe for her.

Has your mom ever had a cognitive or memory test given by a doctor? Or tested for a UTI? Is she on any other medications and do you know if she is taking them appropriately? There are many reasons why someone can display memory problems and confusion (like an untreated UTI, under- or overdosing on medications, dementia, etc). You need to get a diagnosis first, then you can think about what the strategy for helping her should be. Be patient and not argumentative, keep the peace with her so that it goes smoother. Get her diagnosed first.

Its time to place Mom. She should not be living alone. I hope there is money for a nice AL. I placed my Mom at one. In a year the money she had ran out and her house had not sold. She had Denmentia and had declined to the point that she needed a NH. I then applied for Medicaid.

This is a frustrating desease. No rhyme or reason and unpredictable. Your Mom is no longer in charge of her brain. She may have put the bread in the linen closet. We found bags of junk mail in a tall dresser in my MILs house. Why did she just not put the bags in the trash.

You will drive yourself nut trying to figure out why.