brother trying to claim land

hi everyone,my mother has full ownership of farmland,now her brother is trying to get some off her saying he is entitiled to it,it belonged to my mums aunt who reared her and left awill leaving to my mum which was about 6 years ago,about amonth ago see became full owner every thing in my mums name ,but she is worried ,is it true once you are full owner there is nothing he can do.Thankyou

Have you a copy of the will? You would probably be best seeking the advice of a solicitor on this matter.