• Mum being mentally ill

Hello Sir,
My mother aged 80 yrs has been living in Kolkata for more than 40 years. She has been a tenant for the same period. I am her only child married abroad and I have a small child. During recent years she experienced  memory loss, confusion, hallucinations and paranoia which are signs of dementia.She fears conspiracies of neighbours and the landlord trying to murder her.
She ending up going to the police station with these false allegations against the landlord and other people putting everyone in trouble for no reason. Finally the police called me and let everyone off as it was evident that she was not in sound mind.
Everyone is very kind and helpful to her. The landlord is a very nice man. These ideas are just hallucinations and no one is harming her. Mum has had a difficult personality for ever and now with age things are getting worse. 
I have tried to accomodate her in old homes, with relatives , with me and my family but all that failed. I tried to get her treatment but she refused that too and made life hell for everyone  and wishes to be left alone. 
What can be done to safeguard me and everyone else as this can escalate and she may end up going to various higher authorities. Can she be institutionalised involuntarily?
Your advise is highly appreciated.