House occupied

Sir I has given my house to stay my sister &her family as I am working at different placein 2016. That house was purchased by my grand mother and had a registered documentin1963. But in 2012 Muslim crowd of people about 25 members entered my vacant place and occupied front portion though I have a statusco. At that time my friend was staying in my house. Unfortunately he shifted to some other house in 2016 . So at that time I thought that if my relatives staying in my home is better than others. But now my relatives refused to handover my house back stating they protected hosuse. What can I do?. so at that time I tho