Tenant's Rights if Landlord's developing the Property

My parents (along with 2 sisters and a brother) are tenant from more than 30 years in the same house. The Landlord is now planning to develop the property by demolishing the old house to a multi-storied apartment. What are our rights/ claims in that case? We are not that financially well off and could not afford to pay any amount for a new flat in the redeveloped property as the landlord has hinted us that he will consider me half price of the market rate, which will amount somewhere in 15-20 Lacs. We have almost no savings or any other financial mean to afford that. What can we do in such sceanorio if we're asked to evict? Also the Landlord doesn't issue any rent receipt, but we have the electricity bills paid throught out these years but that too is in the name of the Landlord's late mother. What steps can ww take to safeguard our interests?