Salesforce deed Cancellation

Hello, everyone. For ease I am going to reference three persons A, B, C(Me) in this question. So 4 years back A has sold his house which he got through inheritance from his mother to B through Sale deed, but the agreement between them is that A is going to stay in the house and pay the rent to B. After a year, B has mortgaged the house to Me(C) for a certain amount, but failed to pay the amount back. So, after the stipulated time of 3 years, I received the house, and B has transferred the ownership to Me(C) through Sale deed. But, in a hurry, I haven't asked the person A(first Owner) to vacate the house before the registration. Now, when I have informed the person A to vacate the house, so that I can sell the house and retrieve my money. He has refused to do so. After a few days, he informed me that his wife and chidren (Minors) has filed a case in court that, the house is the only property that is left for them, and that A has sold the house to B without informing them{his wife and children(minors)}. He is threatening me saying that the whole transaction from A to B and mortgage from B to C(Me), is going to get void and I cannot do anything about it, and the court is going to give the property back to his wife and children. Is such a scenario possible. What could I do to legally move forward in this situation.