Can my grand mother revoke gift deed

My grand mother now 75 years of age has gifted her property which she inherited from her husband ancestral property to her eldest son in year 2001. At that time the son told him that he is making a will but he made a gift deed and got the property transfered to his name . My grand mother have 5 children , 3 sons and 2 daughters and she has gifted the property to only elder son. That son has left her and is staying away since past 12 years and don't have any relation to her mother. My grandmother feels cheated and want to revoke the gift deed and give the property by gift or will to her daughter(widower ) with whom she is staying for past 12 it possible to revoke the gift deed now after almost 15 years? The property which she gifted to her son is the residential property where she is staying since marriage and the land near surrounding the house. She enjoys the residing on the house, where as the son is living separately for past 12 years. do other 4 children can claim for revoking the gift deed or there share of property from the mother, as property is I heritage from ancestors and is not earned by her or her husbsnd.? Kindly do suggest what could she best do to get back, her property. Can she file a civil case? All valuable suggestions will be appreciated Thanking you