Cheat in property right transfer.

Hello All, My grandparents used to ill-treat and torture my mother and my siblings. To get rid of domestic violence, my parents decided to separate from them. My parents are not well educated and they are economically weak. They did not have enough money to buy a new house. My grandparents gave an offer that they will give help us to buy a house and they shall have ownership right of half of the property. My parents did not have enough case, so my mother gave all her gold jwelleries (costing nearly 70% of property cost). Remaining 30% was added by my grandfather. We bought the new house and started living there in our half. My father trusted his parents, so he did not involve in legal formalities and paperwork of house purchase. We assumed half property was ours. My grandparents cheated us, the whole property and all rights on it were legally was transferred to my grandmother. After the death of my grandfather, we came to know about this truth, Since last 20 years, we are living it that house. Since my grandmother never had good relation with us, she has decided to give whole property including this house to my uncle (father's brother). She has transferred this house to his name. They are forcing us to vacant that house. What should we do now? My parents are not greedy. They do not want any share in my grandparent's property but they want to keep their own house with them. What are options available to us? Thanking you.