Tracing and claiming right over plot acquired by Government

Dear Sir, My grandfather registered a plot in his name in 1955 in Delhi (Khasra 926, Mandawali area near Ganesh Nagar, East Delhi). This area is between Geeta Colony and Patparganj, Delhi. Since the plot was obstructing government's expansion plan, they decided to acquire it and in turn offered some meager compensation to all plot owners including my G.father. The amount was refused by all and it was decided by all that the case be contested. But since my G.father was in armed force services and posted out of Delhi, he could not pursue the case with authorities nor did he accept the compensation. He got retired in 1981 and settled elsewhere. He has all the documents pertaining to registry and map of the plot with him, but we do not know how to go about pursuing this case & claim compensation. Today that area may have been name something else. Please guide us.