My rights on my grandfather property

My father passed away recently , he was a government employee not retired yet. My grandfather has agricultural land and house on his name. He is denying to give me any share in their property even though I told them I will do a fixed deposit of certain amount for their maintenance. Also my grandparents have rasied a complaint in my dad office asking for share in pension and other benefits we received from government. How can I get my share of property and also will they have rights in benefits