My question involves real estate located in the State of: Mississippi

I own a house and 11 acres that was purchased by my parents from my grandparents in 1998, due to financial issues of my grandparents. The deed that was written up only has my grandmothers signature on it. Now my grandparents and my uncle have put a lawsuit out(or however you would word it) against me to claim the land back.

When the land was purchased my parents signed an agreement that my grandparents could live there the rest of their lives, so adverse possession shouldnt be possible for them, or could it be?

If the deed isn't any good, what will happen to the amount of money that was paid for the property? is it a total loss?