What is the name of the issue in which the mother inherits one-sixth, with no son, no grandson, and no two siblings? Is it Al-Akdariyyah, Al-Musharakah, or one of the two Al-Umariyyatayn?

The mother inherits one-sixth in three cases: when there is a lineal descendant, when there are two or more siblings, and in one of the two Umariyyatayn cases (a husband and two parents), where the mother receives one-third of the remainder, which is one-sixth of the original share. If the mother inherits one-sixth in a case where there is no lineal descendant or a plurality of siblings, then it is one of the two Umariyyatayn cases.