Mom made a Trust, Living Will and POA.POA (sister) is spending money strangely

Mom has dementia and Alzheimer. Mom has told different family members that she thinks her money is gone. Sister admitted to adding her name to mom's house. Sister believes everybody else is lazy and she deserves all the money.
Does Mom's Trust stay in effect and can my sister have mom sign documents when she has had Alzheimer for 5 years?
She sends some family members spreadsheets showing how often we visit. Do we have the right to request all the moneys spent since sis took over? An accounting?

You mom cannot legally be held to a written contract if she has Alzheimer's. You need to involve an attorney in this matter, and do it quickly. No amount of advice on here will be more valuable than that. Consult an attorney NOW.