Right of grandchildren over grandfather's property.

I was married in 2001, and i have two kids, a daughter and a son. I lived at my in-laws' house for about eight years. Now I'm living with my parents and my kids, because my husband was unemployed, a drunkard and a gambler. I worked as a music teacher and raised my kids through my income alone. However, my husband snatched away all my earnings and sold my jewelry for his abuse. He even created a ruckus at the school I worked in, forcing me to give up my wages to him. My in-laws are old and couldn't manage to oppose him when he ill-treated us. In order to protect the future of my kids I left the in-laws' house in 2009, however, since then I'm unable to support their education and living as they are growing, with my meager salary as a music teacher. My father-in-law is a state govt. pensioner, and has two sons and two daughters, apart from my husband, all of whom are well-settled. He owns a house in Ranchi, Jharkhand. I want to know if my children have any rights on their grandfather's property? If yes, then how can they receive their share? Also what is the time required for it? My daughter is twelve and son is ten years old.