My brother( got job by karunya scheme) is not taking care of my mother

My younger brother, he took job under karunya scheme in irrigation department after my father passed.( He is state government employee ). After his marriage he was staying separately from my mother. And she is alone staying. He is assaulting some times and scolding bad words for her pension amount. I am staying out of country (working in Dubai). He promised he will be take care about my mother, when he taken job. Now he is not taking care about my mother and he is scolding several times in public. What actions can I take, since she is mentally upset and daily crying. However I will take care about my mother in future. In meanwhile I don’t want to get any problem from my brother to my mother. If he take care properly it’s good otherwise, I don’t want get any problem from my brother to my mother.