My Mom is 96 year old with Parkingson's dementia which is progressing very slowly. She is constantly misremembering what she has in her space.. And consequently is constantly blaming the aide for taking her things. For example she has a small doll collection about a handful and says that she had 19 dolls and most are missing. She believes the aide is always taking one. She will yell at the aide about taking her stuff. I try to comfort my Mom that no one wants her dolls and that I know they are still all there. But there is no reasoning with her. It is so distressing because it makes my Mom miserable. She has also started rummaging thorough her things on a regular basis. Even though I have help I'm constantly dealing with my Mom's distress since she lives with me.
I agree a low dose of Ativan to calm mom down is a good idea.
Also, give her a big box of things she can rummage thru to her hearts content. Rummaging can offer a measure of comfort for individuals with dementia, offering recognition of familiar objects and a way to find purpose and meaning.
Giving mom some small job like folding towels or sorting spools of thread may help her as well.
Good luck to you.
So often did this happen with my partner's mother, accusing her long serving Wilma over and over of this and that, that now when either partner or I lose something we always giggle and say "Wilma took it".
There is no reasoning, and there is no argument with a disease like this. Simply express your sympathy with her and attempt to move on. When obsessive thinking and acting out becomes continuous speak with doctor about some try at low dose anti depressant. That can sometimes help a bit. But often doesn't.
At some point you will be left with choices about how long you can continue home care with someone who really needs several shifts of several people each to deal with the continuous problems this condition brings.
Good luck.
Have you tried taking pictures of her things, so that when she thinks something is missing you can show her the pictures to reassure her that they're still there?
That may or may not work, but the important thing for you to remember(since your brain isn't broken)is that your mom can't help what she says or does, and that things will only get worse as her dementia worsens.
So if her care is getting to be too much for you then it may be time to think about placing her in a memory care facility where you can get back to just being her daughter and advocate and not her stressed out caregiver.