My Mom suffers from dementia, depression and is very angry. My siblings and I need help with her. Advice?

She is almost 85, and unreasonable. She gets angry quickly, occasionally becomes violent, and makes unreasonable demands on us. We believe she is living in the past (about 65 years ago). Hallucinates/thinks someone is living inside the wall, spying on her. She has been known to wander, and now she is demanding to get a one-way flight ticket to Puerto Rico, and has not contacted anyone there. All her family over there has died. What can we do?