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.
Management of the Masjid resembles the role of the endowment keeper or the agent who acts on behalf of the donors and both the keeper and the agent must abide by the conditions stipulated by the endower and the donor, and try their best to do what is beneficial to him. In other words, if people donated money for the purpose of building a certain Masjid, it is not permissible to spend their donations on setting up another project or building another Masjid. However, if there is a benefit to do that, such as if there is some money left after building that Masjid, there would be no harm to spend them on building another Masjid. As to spending the money on another project, such as building schools, the majority of scholars forbade it. For further information see Fatwa 89338.
The ethical code required in this position is truthfulness, honesty, keenness to accomplish the public interests in conformity with the Sharee’ah, and giving precedence to this over one's own desires and personal motives.
Allaah Knows best.