Do the children of a daughter who died during her mother's lifetime inherit from their grandmother after her death?

You do not inherit from your grandmother's estate because the children of a daughter are not heirs; rather, they are considered kin (dhawu al-arham). As for the grave, it is an endowment for its occupant, so no other person may be buried in it as long as the deceased remains within it. However, if the deceased has decomposed and turned to dust, it is permissible to bury someone else in it, whether they are among the deceased's heirs or not.