Property issue

Hi all, Pls guide me on below issue. My mother in law brought aparment on her two sons name by selling land on her name. The property registered on two son name in cidco. Its almost 10yrs now and the only younger son paying all maintenance and property tax and staying since 6 yrs in the flat and spent huge amount in renovation of flat. Now elder son claming his share as his name mentioned in property as co applicant. Now my mil want her property back from sons as both not given single penny at the time of purchase. Is their any way to get back property from sons or soley the younger son can be owner of apartment. Regards.