Hi
The property of your maternal grand mother will legally be vested with her legal heirs.
Since both your uncle and your mother are no longer alive, in absence of a WILL by your maternal grand mother, the property of the maternal grand mother will vest in equal shares with your uncle's 3 children and yourself(property divisible in to 4 shares)
However if you want to claim all of the property to yourself, then
a) you should file a case stating that your grand mother was disowned by her son's children subsequent to the demise of her son and that you were taking care of your grand mother. It will be great if you can submit proof of you taking care of her (medical bills, house accomodation, food expenses etc)
ALTERNATIVELY
b)If you can demonstrate to the court to that your grand mom's wish (it can be an oral will also duly stated in court along with 2 witnesses), then you can claim all of the property to your name based on Oral Will..
So technically if you wish to claim all of the property to the exclusion of your cousins,
a) you need to prove and demonstrate the factum of the demise of the father and
b) Prove that the last wish (Oral) of your grand mother was to bestow the property in your name.
Hope this information is useful.