Need guidance

Hello My query is my father has gone missing and has left no will. So how should I proceed. Also my brother and his wife verbally abuse my mother who is physically handicap. He does not support her finacially.My brother refuses to handover the property documents. What are my rights and my mother's rights? What legal step can my mother take? They had physically hit her and a police complain is filed against them. She wants to evict them out of the house. The flat is in my father's name. Also we have a small gala which is given on rent and the rent goes to my brother. The company I think is registered under HUF. What right do I and my mother have? Please guide as my mother is diabetic and handicap. I want her to lead a good dignified life in her old age.