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 Diyah (blood money) of the fetus is an obligation on whoever carried out the abortion. For instance, if this sister took a medication and aborted the fetus, then she is obligated to pay the Diyah. All the heirs of the fetus will inherit from this Diyah except those who carried out the abortion amongst them. As regards the father, if he caused the abortion but he did not carry it out himself, then he is sinful but he is not obligated to pay the Diyah. For more benefit, please refer to Fataawa 101103, 128722, 98739, 102388 and 85558.
Moreover, the father of the mother does not inherit as he is a maternal grandfather and he is not an heir in principle. The same thing applies to her sons; they do not inherit because she got pregnant with them after the death of this fetus. With regard to the grandmother on the mother’s side, then she inherits despite the existence of the mother, because the mother is prevented from the inheritance as she was the killer, and so, she does not prevent others from the inheritance, according to the view of the majority of the scholars . Ibn Qudaamah said: “The one who does not inherit does not prevent others from the inheritance, this means that whoever does not inherit because he has a characteristic that prevents him from the inheritance, like the difference of religion (between him and the inherited person), slavery and killing (the inherited person), then such a person does not prevent others from the inheritance according to the majority of the scholars – from among the Companions and the Taabi’is (the generation that followed the Companions) – with the exception of Ibn Mas’ood and those who are of his opinion.”
Therefore, if there is no other heir other than the grandmother [the mother of the mother], then she takes the entire Diyah.
Finally, it should be noted that in matters of inheritance and the like, one should take his case to an Islamic court or to an authority that acts on its behalf, because the court may determine the heirs and so forth, and this will prevent the door of disputes.