My eldest sister was my mother's paid caregiver. The caregiver informed all the siblings that my mother had Dementia and Alzheimer's. Which later we found that this was not a true statement by way of one of her hospital stays, which leaves us to believe that she was over medicating my mother. After my mother's demise the siblings were given pictures of my mother with two black eyes and a busted head. My mother was at one time the payee for my daughters ss and ssi, which the money cannot be accounted for. Prior to her demise I asked my mother about my daughter's bank account she informed me that she had closed the account and did not know where none of the money was. The caregiver was also questioned and I was informed that she was going to look into it, which did not happen prior to my mother's death. My sister was also named as my mothers personal representative in her will, whereas she refuses to act and has changed the locks on the house that was equally divided between the siblings in the will. She refuses to take calls from any of her siblings.
However, there is the issue of the missing money and your mom's house that should be able to be brought to court.
Your best bet would be to get in touch with an elder law attorney. They are not cheap, however, most states and/or cities have lawyers that do 'pro bono' work or work for Legal Aid. Do an internet search for your local Legal Aid Society.
In the meantime, gather as much paperwork about your mom's 'care' and how your eldest sister was paid, your daughter's SSI and bank account as you can. Save the pictures of your mom's bruises and any texts or e-mails from your eldest sister. If you have a copy of your mom's will, that would be great. If you don't, but know the lawyer who drew it up, contact them - they probably have a copy.
I wish you the best and my sympathy for your mother's passing.