Purposely trying to foul the social status of the tenant..!

Hi My Sister is residing at Coimbatore for past 9 years in a Rental home, recently she decided to shift to a new home [rental] during time of vacating the current house owner claims that the rent for 1 month has been missed. 1] She was residing in this home for rent from 2010 to till date. 2] No lease/rental agreement were signed. 3] She has paid rent, Water tax & property tax on behalf of the owner in local panchayat office till date. 4] Until 2012 rental was paid via NEFT, later for one year he purposely received the rent as cash on hand - for one year [2013] directly by visiting home. 5] After 2014 again he requested to pay via online via diff account no, [paying till date]\ 6] we have bank statement on hand for all the above transaction. Now referring only this bank statement - he is forcing her to pay the rent for 2013 complete year. He do this purposely to foul her social status & dignity. we escalated to our neighbourhood & persons nearby - all says this is not good & not genuine to raise this issue purposely after 8 years. Kindly help her to approach this legally & ensure she do not loose her dignity please. Thanks