How to get property registered when the last owner died

My father brought an property from a person in 1994 with proper stamp paper along with witness person in the village.. the agreed amount also settled to the person. But it not registed in revenue department. But the land tax ,water tax and electricity bill paid update this month from 1994. Since my father moved to new place .. He want to sell that property. For registration the first owner need to sign.. So he approched to there family. And the person who sold had died and he did not have any children..Her wife agreed to sign.. But during registration she is not signing..My father told if you want take this property and give the current market value and extra construction which I did.. For that also she is not ready to take . And not leaving to sell Please give me some input . How to proceed?