Divorced ex nuisance if allowed to stay same house after divorce

A friend of mine got divorced a few years back. Unfortunately his ex wife got fairly unwell and the son requested if he could get her to Delhi for treatment. Out of goodwill and humane reasons my friend allowed his ex to come live with them and get treated. With time she got a stroke and my friend did everything from ICU to bear hospitalisation expense and got her back home to nurse her to good health again. She got slightly paralysed on left limbs. It is 3 years now she has been living with him. The son who got her, left to live abroad and again out of goodwill this lady was allowed to continue living in her ex husband's house. She again got a 2nd mild stoke. This guy is doing everything to support her. Today, no one from her side of the family wants her back. She has become his liability. Plus, his biggest concern is that since she is fairly crooked and has gained alot of sympathy there is no way she will go now. If she is made to then she will create huge nuisance so that this guy never moves on with any other lady. How to smartly handle this so that no legal implications.