In case a person divorces his wife and the divorce is revocable, and this person dies before the revocation of the divorce and the expiry of his wife’s waiting period, then this woman will get a share in the inheritance, for the marriage is in force.
If a person divorces his wife during his sickness culminating in his death, even though the divorce is irrevocable or pronounced thrice, and he died before the expiry of the waiting period, even then, this woman will get a share in the inheritance. And in order to make her inherit, the longer of the two waiting periods shall be taken an operative in the following manner.
The waiting period following a divorce is three menstrual periods and the waiting period following the death of the husband is four (lunar) months and ten days. The waiting period out of the two which lasts longer shall be prescribed as the waiting period for the aforesaid woman so that the woman may get a share in the inheritance as far as possible.
And if a person divorces his wife, irrevocably or by pronouncing it thrice, prior to any sickness culminating in his death, and a few days later he passes away during the period of his wife’s waiting period, then, she will not get a share in the inheritance under this situation. However, if the divorce given was revocable, she will inherit.
If a wife secures a separation from the husband at her own instance khula within the period of his sickness which culminates in his death, then, she will not be an inheritor, even though her husband may die during her waiting period.
(Taken from Maaruf-ul-Qur’an by Mufti Muhammad Shafi Usmani)