daughter in law abusing parent in laws

Hello I am senior citizen. My daughter in law is of abusive nature, she harass me, my wife and daughter. My son is under influence of his in laws, but now he admit that she beats him as well. But he don't say anything to her when ever she abuse my family, he might be under pressure but he never come to us and discuss things and blame us every time. Her family members visit every month to our house. We even disowned our son but still he is not leaving our house. Daughter in law and her family gives threats to us that we will put case on you under dowry and domestic violence and demands money or property from us. We cannot live like this in constant fear of threats and abusive environment, my daughter is still unmarried and working they threaten her as well and said awful things about her character. We want to live peacefully in our own house and I don't want my daughter life's get ruined because of her. Please suggest what we can do so that they vacate our house and don't do any damages