Harassment of a lady Senior Citizen by her son & daughter-in-law

Dear experts, I am asking the question / seeking solution on behalf of my Mother. She is a widow who is 65yrs of age. We have two properties. One is shop which is in name of my mother & my late father jointly. Seondly wwe have a house which is in name of my late father. My brother got married on July 2013. Since then his wife has been threatening me and my mother that she will file a false dowry case against us if her demands are not met. She wants that we should give shop to my brother so that they can sell it and have money. and her second demand is that we should sell our house and but a double story house in their name. 5 days back, both my brother & his wife created a lot of drama at our home because of this. They threatened my mother that if she doesn't fulfill their demands they will either commit suicide & blame me & my mother in suicide note or else they will file a dowry case against us. On that very day I filed a police complaint against them. Kindly guide me if my mother can restrain them from entering out home? They have never paid any bills / maintenance for home.