The correct answer is (d). A waqf in favour of utter strangers is not a valid object of Waqf under Muslim Law.
A waqf is a permanent dedication of property for a religious or charitable purpose. The object of a waqf must be lawful and beneficial to the public. Celebrating the birth of Ali Murtaza (a), granting to an Idgah (b), and payment of money to Fakirs (c) are all lawful and beneficial to the public, and therefore valid objects of Waqf. However, a waqf in favour of utter strangers is not lawful or beneficial to the public, and therefore is not a valid object of Waqf.
A waqf in favour of utter strangers is a waqf that is made for the benefit of people who are not related to the waqif (the person who makes the waqf). Such a waqf is not valid under Muslim Law because it is not for the benefit of the public.
The purpose of a waqf is to benefit the public, and a waqf in favour of utter strangers does not do this. Therefore, such a waqf is not a valid object of Waqf under Muslim Law.