You need to seek advice from medical professionals and attorneys, not HN.
fake quote> Who the fuck should I contact? A medical professional? An attorney? The police? The FBI?
Luckily I never had to deal with something like this, so I have no idea. Is there some non-profit organization that can give advice? (Something like AA.)
Medical (i.e., Mom's doctor) to discuss her mental state.
Attorney - likely in concert with doctor - to possibly see about obtaining power of attorney for degraded mental state.