Can the relatives of seller claim back agricultural land after 30yrs

Dear Sir/Mam. I recently heard a situation regarding the Agriculture Land. Mr X sold a land to Mr Y, With two people, as the proof. It has been done before 30 years. At that time they just had a Notary form. But now, the situation has come that Mr X soninlaw filed a case against Mr Y noticing that he is using his Land. The gun Points over here are • Mr X got expired • two people who were proof were also passed away • Mr X wife knew the facts. But now we don`t know whether she is influenced by someone or something. So, she is not accepting the facts. • Mr Y was cultivating the Land for last 30 years. Since Mr Y made a land to a useful one.So, Mr X wife and soninlaw want their land forcefully.  So how it can be handled?