Is it permissible to give zakat to two orphaned sisters from their father, and to a brother who is preparing for marriage and has difficulty affording the costs of his apartment and exorbitant furnishings?

The maintenance of the two daughters is obligatory upon their disobedient father who neglected them. If the father is unable or refuses to provide maintenance, then the mother must provide for them, and it is not permissible for her to give them from the Zakat. As for your brother, who is indebted for the price of the apartment and is unable to pay it, he is considered eligible for Zakat. Similarly, a person in need of marriage who is unable to cover its costs may be given from the Zakat what suffices his need without extravagance.