Father passed away 22 years back can society stop transfer of flat?

we have a flat in my father name joined with my mummy in mumbai. 'my father passed away 22 yrs back my mother is still there.we are 2 married sister and 2 brother. my sister claim for the share of that flat.we are muslim and we want as per the islamic law,but they want as per indian law.but indian law says that before 2005 fathers death they cant claim.and they wrote letter to our society not to transfer in my mother name and also my mother can't sell this property as they are having objection.the society because of this letter telling us to do the heir ship of this flat,please help me?