Brother and his wife harassing and torturing my mother

Respected sir, my father is a teacher and we are 05 brothers and 04 are living out of city.our eldest brother and his wife are living with my mother. They are torturing my mother and mentally harassing. Even brother wife threatened her to file a case of dowry. Brother wife called police to engage in fake case of domestic violence. Brother is a alcohol addict and both become abusive to my mother. My mother has a severe lungs disease too and alone at home. Kindly look after the matter as we are very anxious. What should we do?