Cancellation of registered document

My grandmother have three children my mother ,my uncle and my aunt in 1983 my grandfather bought 600 sft land and put my grandmother's name. My uncle split the 600 square feet land into two parts 300 square feets of land he builds a house in 2005 ,he wrote gift deed from my grand mother in 2010 my grandfather suddenly died with heart attack then onwords my grandmother distrubed and suffered with mental illnesses she committed suicide in 2011 and 2012 .in 2011 my uncle forcefully registered 300 sq feet land with his name, my grandmother sucided in 2021 my uncle also died with heart uncle's wife considering all documents she take overed all my grandmother's properties with the name of my uncle's name .my mother and her sister didn't get any property from her my grandmother's postmatram and police report mentioned she have mental illness .is there any chance to cancel registration documents,and fight against for property in court to cancel the registered document because of my grandmother's mental health problem.