Succession / legal heirs of women

Who are considered to be the legal heirs of Hindu women? In this specific case, my sister is a widow, with 3 children. She has 3 brothers and sisters including me. Our father has passed away, he left a Will giving all of us - including her - a share in a flat. His will is still under probate. In case she dies without leaving a will, to whom will her share in the property go to - us (her siblings) or to her children ?