Gift deed

Your mother can't  gift the property owned by your father to anyone until and unless she has become absolute owner of property. If your father died intestate then his property rights devolve to his all legal heirs equally including you.

How does she become absolute owner

Your deceased father's property devolves equally on all his class I legal heirs.

You are entitled to a share in it as a right.

You can file a suit for partition and claim your share with separate possession.

You posted this query in this forum in another way, why repeated?

The posting suggests deeper issues. Please post complete facts.

Other than you and your mother, who are the legal heirs of your mother? In other words, how many are your siblings? Are all of them alive? If not, who are their legal heirs?

All the more, who is this "grandson"? Is he your own son?

 

We are three sisters and one brother. The grandson is the son of my brother All of us are alive 

You can file a suit for partition either alone or combining your female siblings and seek for your rightful share in the property left behind by your deceased father who is reported to have died intestate. 

The property will be divided into five shares. 

The gift deed executed by your mother in favor of your nephew is not maintainable or legally valid.