While considering the case of spinster, the property would go to the parents as they are the legal heirs. In case the parents are no more, her siblings would enjoy the property. In that situation, the property is to be divided among the number of siblings of the dead parents.
In case of availability of a will, the property would go in favour of the person/ persons recommended by her.
Here one point is to be noted, all the siblings are entitled to get equal shares of the existing property. It may so happen that some of the siblings are dead and in that circumstances, the legal heirs would be their children. This is within the compliance of Hindu Succession Act as amended in 2005.
As per your submission, your father and your aunt are the only survivors as the legal heirs, they can claim the property with the production of the succession certificate released by the court.