Registery of the property-Plot

Dear sir/Madam My father bought a property(Plot) 15 years back with power of attorney and possession letter from old lady whose husband was dead . she gave power of attorney and possession letter to my father and his son signed as witness . My father paid all the government taxes ( NIT tax) on behalf of earlier owner that time itself, but registry was not executed because of some financial condition of my father. After that my father tried for one year , get it registered but it didn't happen. We were very young that time , we were completely unaware ,after that father was dealing with health issues, So it didn't workout . Now when I went to get it registered in registrar office. Officials told me that akhiv pratika ( property letter ) includes name of old lady and his son. To execute the registry , presence of both son and mother is required. Now I contacted them, they are reluctant to help and are saying they do not want to get involved in that property. Please kindly tell how to move forward , in such situation.