All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
Building hospitals is not among the Zakah disbursement channels; therefore, what your mother and sisters paid is not Zakah, and they are still liable to pay it; and it is due on them to pay Zakah once again, so long as they did not depend, in giving out Zakah for that project, upon a Fatwa of a scholar. If they depended upon a Fatwa of a scholar, we hope that they would be free from obligation.
Allaah Knows best.