Mental harassment

I am an 27 year old daughter and wish to talk for my mother. My father is continuously torturing my mother for every single thing. He follows her to kitchen to anywhere she goes. She cannot step out of house without his consent. He is retired since 2 years. These things have gone to peak after his retirement. But , he was always like this since years but earliar neither I nor my elder sister could speak up for her. He doesn't like both of us (2 daughters)too. He makes my mother pleed for every single penny. If she is eating something, he will make her feel it's cost. Money minded he is. He don't wish to spend anything on anyone accept himself. I am on maternity right now for my first child and have come for delivery at my father's place. He has tortured me too with his harsh words, that too at this stage of my health. This is why am seeing all this in these months an feel that my mother is not safe here. We sisters will leave after 2-3 months..then my mother will be alone again..n I don't want my mother to suffer the extreme harassment after i go from here. What is the best possible way out to deal the situation? There is no property or any amount of money in my mother's name. Everything is with father . She is a home maker. So she has to ask for money from him for household reasons and that is the point where he insults her that she is incapable of even bread. Please help. I wish to help my mother.