1) how did your grand mother give property to your brother?
2) was it by gift deed duly stamped and regd?
3) once you purchased propert by sale deed you would be absolute owner of the property
4) if account had become NPA in 1989 what was bank doing for 17 years ?
5) claim of bank appears to be barred by limitation
6) if bank takes legal proceedings you have to contest the same on merits