Is it permissible to conduct the marriage contract of a girl inside the hall [ceremony room] in the mosque while she is in menses?

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 is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

If this hall is designed for women to perform the prayer in it, then it is not permissible for a woman in menses to enter it, as in this case the ruling that applies to this hall is that of a mosque. According to the most preponderant of the two opinions of the scholars it is not permissible for a woman in menses to stay in the mosque. Nevertheless, if this hall is designed for ceremonies and not as a prayer room for women, even if sometimes they perform the prayer in it, then it is permissible for a woman in menses to enter it. Finally, it should be noted that the presence of the girl is not a condition when conducting the marriage contract, it is enough to obtain her consent, and the contract could be conducted while she is outside the hall. 

Allaah Knows best.