All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
The granddaughters have no right in the inheritance of their grandmother from the mother's side, as the religious ruling known to the scholars reads: "Whoever is related to the deceased by a female, he has no right in the inheritance." However, there is an exception to this rule, which is the brothers and sisters from the mother's side.
Therefore, the inheritance of the grandmother of the deceased will be divided among her children, the male twice the share of the female. Her sister does not have any right in her inheritance because of the existence of other heirs. Allaah Says (what means): {If a man dies, leaving no child but [only] a sister, she will have half of what he left.}[Quran 4:176]. Therefore, Allaah conditioned the non-existence of children for the sister to have a right in the inheritance. As regards the grandchildren, they have no right in the inheritance because their mother does not inherit from her mother because she died before her, and they, themselves, have no right in the inheritance of their grandfather.