Is zakat obligatory on the money of two orphaned, mentally disabled twin sisters upon the passing of a year, knowing that they have no income other than this money inherited from their father?

If the share of each disabled woman reaches the nisab (85 grams of gold), then zakat becomes obligatory on it. Her guardian must pay it when a year has passed. The obligation of zakat on the wealth of disabled women, even if they have not reached puberty or are mentally incapacitated, is the view of the Shafi'i, Hanbali, and Maliki schools, and it is the most preponderant opinion.