Settlement deeds

Father A has settled separate property to son B,C and register based on that property tax,patta changed to name of B,C .C build house where A resides .Near by B resides.Family issues C left the place and shifted to father-in-laws house.After 2 years A and B is not allowing to enter inside creating false image on C.Forcing to get it back. OK said C, take it but return the money which we spent to build the house upstairs.No said A and B .A said we educated you and provided food shelter till marriage it got equal move from this place. my question is 1. Without the knowledge of C can settlement be cancelled by A. how to know? 2.Will i get my money back which i spend?-C 3.Parent A got sign from B,C that till the death A resides in C downstairs.Not allowing to C to leave rent,water,not opening the main door. passer by near by resides creating false imagination on C. please give a support to come from this situation.your advice is very valuable of C and this information is given by C wife.