All perfect praise be to Allah, The Lord of The Worlds, and may His peace and blessings be upon our Prophet Muhammad and upon all of his family and companions.
The committee isn’t permitted to use any of the Mosque’s donations for other than the purpose for which they been donated for because in principle, donations are distributed according to the donor’s condition and intention as the same rulings of the endower’s applies on the donor and his donations are distributed only wherever he wanted to.
In this regard, Al-Imam Al-Jowayni (May Allah have mercy on his soul) said: ” The condition of the donor has to be fulfilled exactly as been conditioned, such as: the eligibility of the person receiving donation, the amount of donations, the number as well the order of the beneficiaries because only the donor has the right choose what has been mentioned accordingly and to specify the amount and the method of distribution.” [Nihayat Al-Mataleb vol.8 pp.362].
Besides, Al-Imam As-Shirazi (May Allah have mercy on his soul) stated: ’’Donations are distributed according to the condition of the endower .i.e. the eligibility of the person receiving donation, the amount of donations, the number as well the order of the beneficiaries in addition to excluding and including whoever he wants, since the righteous companions (May Allah be pleased with them) wrote down their conditions while making endowment.’’ [Al-Mohadhab vol.2 pp.328].
Therefore, the aforementioned committee isn’t permitted to take any amount of the donations regardless of their purpose as well in order to be on the safe side, they are required to gather some donations for the purpose of financing committee’s administrative affairs related to the Mosque so long as the donors are notified. And Allah knows best.