Mother Gifting Away Her Father's property through Gift Deed

2 years ago

My Grandfather had 2 Daughters. He wrote a Will where he gave his house to his Eldest Daughter. To his second Daughter (my Mother) he just mentioned in the Will that she will just get to draw the Interest from the Fixed Deposit that he has put in her Name. He has also mentioned that since the Eldest Daughter does not have any Children, the house is willed to any of her (Eldest Daughter) future born children or heirs and after that to any of the grand children of his daughters. But he has never mentioned that my Mother has the right to own that property.
My grandfather passed away after writing the will which was registered in a sub registrar's office. My grandmother too passed away. His Eldest Daughter passed away with no children. So my Mother was the only Survivor, but with no right to own the property as her name was not mentioned in the Will. My Mother has 2 Sons and 1 daughter - which is me. She during her lifetime Gifted away the property to her Second son leaving nothing to me or my Elder brother. Can she gift away a property on which she has no rights and only the grand children had the rights? Can I contest that Gift Deed in court? Can I ask my brother to show us the Gift Deed?