What to do there is a property disupte

I have farmhouse near Imagica, where my grandmother stays from past 40 years. She & my grandfather have got this land from our relative in the year 1962, However, because the landlord was my grandmother cousin in relation there was no paperwork done. All, the deal was done on the trust factor. Now my grandmother cousin expired who gave the land to her and now after 40 years staying there landlord son is saying it is his property and he will allow my grandmother to stay there till the time she is alive and later he will take the whole property back. Now the total property is around 10,000 Square feet which include our house and land around a house which has mango trees, water boring, and whole wall fencing. But he is ready to give us the house because electricity bill and property tax are on my grandmother name, So he said he will give us a house and will take rest of place under his control.The day my grandmother has heard this, she is crying and left hope of leaving. PLEASE HELP!!