Dear Mr Vikrant, You need to take a succession certificate from court in your name by mentioning in the court that both the other legal heirs of your father are insane and of unsound mind,as according to the law no person of unsound mind can own, inherit any property in his /her name. However, a guardian is to be appointed for that property who will only maintain that property for their welfare only. In this way after getting a succession certificate exclucive in your name you can get change the ownership in your name with the registrar properties.
You are advised to get a help from a good and experienced Advocate of this field only otherwise other shares of the property will not come clearly in your name.
you can contact me any time for the purpose and need.