Ancestral property dispute

Ancestral property dispute My father has 4 brothers and 3 sisters and out of them 2 bro and one sister not married. All of them deceased now except one . RTC has name of my grand father and , his bro & sisters ( my fathers name is not mentioned anywhere ) . Now one of my dads niece claiming her rights and I have no idea any will is written . One of them claims all the property is not ancestral and earned by them , some r declared one. We r Christians . My name was in the old ration card and voters card too . Can I claim right for house and property as my grand fathers name is there ? , if my grandfather's name is absent , and my fathers name is not there in property , is there any chance I can claim the rights . My parents got married in the same house and my dad is not alive , what are the my mothers rights over inheritance ? We r Christians . Thanks