This is not ancestral property.
This property is your grandmother's own and absolute property.
She need not take the consent of her an other surviving daughter to transfer the property to her youngest daughter by executing a registered gift deed.
She has transferred the property during her lifetime which is legally valid transaction.
In this neither you nor our mother, if she was alive, can stake a claim for a share in the property as a right.
The ancestral property shall be from from male descendant and that too it should have devolved on three generations to become ancestral in the hands of the fourth generation.
No suit for partition or any other reason is maintainable in this regard.