Rights of hindu girl who married a muslim

Merely marrying a Muslim without conversion will not deprive the girl of her rights to ancestral property. See section 26 of the Hindu Succession Act, 1956.

Yes.  Under Sec.26 of the Hindu Succession Act, 1956 Where, before or after the commencement of this Act, if a Hindu has ceased or ceases to be a Hindu by conversion to another religion, children born to him or her after such conversion and their descendants shall be disqualified from inheriting the property of any of their Hindu relatives unless such children or descendants are Hindus at the time when the succession opens.

Thanks to all for the prompt reply and clarifying the doubt. 

Facts posted are incomplete. How is that the property is ancestral?  What is the circumstances under which the granddaughter is having a claim over in the grandfather's property? What is the chronology of events?