Denial of death claim of employee as educational certificate fake

My father is a govt employee .He was appointed in 1980.After 27 years of his service department calimed his educational certificate was fake. Dept. Stop his salary and enquired about that. In that period he died in 2010.His dept didn't take any action aginst him except non payment of salary. Now my mother and me claim death benefit dept. tell us his appointment was based on fake cerficate so we can't calim any benifit. Now my question is that after 30 years of doing his duty my father died and now we can't claim any benifit .Tell me we should move in high court or not.