Authorization of will of Death person

Hi, I'm from Kolkata. My grandfather(died in 2011) had a land and the land is registered with his name. In 2005 he made an will (will is not notarized and registered,but signed by witnesses and lawyer) by mentioning that the property of him will equally distributed in between of his 3 son. He had a daughter too(died in 2016). But my grandfather doesn't give her a single percentage of his property. But after death of his daughter her son claiming a share of her. Shall we deny the claim of her share according to law which is claimed by my aunts Son ??