Yes your grandmother is also equal stakeholder of the property of your deceased father. Your father’s legal heirs will be your father’s Mother (grandmother), your father’s widow (Mother) Sons and daughters of your father. All the above persons that is your grandmother, Your mother, Your sister and you all will have equal share in the property.
Under the Hindu law, property is divided into two types: ancestral and self-acquired. Before 2005, only sons had a share in such property. So, by law, a father cannot will such property to anyone he wants to, or deprive a daughter of her share in it. By birth, a daughter has a share in the ancestral property.
Since your father passed away intestate his property has devolved through succession equally on all his children including daughters. The share of deceased children further devolved on their respective legal heirs. Any heir is at liberty to file a suit for partition to cull out his share in the property.
If your grandmother do not need the share in property then she also can gift her share in your favour or make a will in your benefit. She does not need consent of anyone to give her share or no one can force her to give her share.
Reference: Hindu Succession Act