Regarding property

My problem is that my grandfather divided his land to his 8 sons ..in which three of them has share on the same land according to his division..he didn't made a will and he is no more now...now one of the brother is not mentally fit so he is caring by his elder brother whi is one of those three brothers ..now the last third one brother died earlier .he has wife or son..she left after the death of my uncle and never came to look out ...even in the death of grandfather.now the prb is that the elder brother WO take care of mentally disturb brother started to make house which was made by grandfather jST because grandfather said to that elder brother to complete that house...he had spent 5.5lacs on that after completing his work he went to his joining place as he is in cisf so his holidays was completed now the wife of my chachag came to that house and throw out the things out of house which is trespass and locked the house.....now she is claiming that whole property that house or land on that area is only her share....so please tell me what can happen in this case in favour of my uncle...