Grandfather's tenant since 20 years encroached the property

Dear Honourable Om Prakash Ji

I really apreciate your positive feed back about the query, I agree the statement should be little more clear I apologise.

I own a family property gifted by my GF (He Passed away long time ago) with tenants living since 20years, After looking into the property card and documents I relaized the tenant has been illegally using a room as a kitchen and upper head conceret floor and added a bathroom behind the room ( there is a toilet out side the house ) 

I'll copy and paste few from my QUERY:

The property card is proving his area of room is 200 sf

We made several complaints to Municiple in writting.

An advocate Notice has been served 5 years ago twice 

Land assesment record covering only total land area which is 1300 sq

Negotiation  failed. Because  The tenant is working in the high court 

What do I need to prove the breach of contract to evict him or simply would you recommend anything to win the court battle?

Thanks for the time

Sami