old tenancy

In the year of 1950 my grandfather was a tenant of the ministry of rehabilitation then in 1952 that property was purchased by some other person in the bidding. And my grandfather started paying rent to the landlord. after few years landlord got expired and his son to whom that property belong to according to the will, filled a suit to increase the rent and eviction of the premises. My grandfather won that suit in the year of 1975 court rejected the suit for eviction and told to pay the same rent to my grandfather. Now my grandfather expired in the year 2004 and grandson of the landlord filled a suit saying that we are not his legal tenants and since original tenant died to vaccate the premises. And now lower court has ordered us to evict the property and to handover the same to the legal representative of the landlord after the case proceedings of 7 years now and to pay the charge of around 3 lacs as suit for damage and recovery of possession since the death of my grandfather for around 8 years I need experts advice as to what to do further with this please suggest and if I appeal in the next level how far I can go and until how many years will able to survive. And what could be the favorable results for me If I take this forward which anyways I will be doing thanks Please assist