All perfect praise be to Allah, The Lord of The Worlds; and may his blessings and peace be upon our Prophet Mohammad and upon all his family and companions.
A person volunteering to distribute charities and Zakah(Alms) funds is a proxy of the donors/givers. A proxy is trusted, so the donations given to him are a trust that he is obligated to preserve and deliver to their eligible recipients; otherwise, he shall carry the burden of betrayal, and if he doesn`t administer them as should be, or fails to do so, then he has transgressed and sinned; therefore, they remain a debt that he must pay off so as to be freed from the liability. Allah says {what means}: “O ye that believe! betray not the trust of God and the Apostle, nor misappropriate knowingly things entrusted to you.”{Al-Annfal/27}.” It is imperative that the authorized delivers these donations to their eligible recipients, and doesn`t benefit from them, even if he is one of the eight categories eligible to receive Zakaah(Zakah disbursement channels), such as the poor or needy. This is because he isn`t allowed to make personal benefit out of what he has been entrusted with, and giving donations, in principle, is governed by the intention of the donor/giver and the terms set by him. A donor is like an endower, and in principle the terms set by the endower must be adhered to, so donations must be spent as he sees fit. Moreover, he could refrain from making any donations once he realizes that the person collecting them takes a share.
In addition, a proxy in alms isn`t considered amongst those employed to administer the funds in order to be entitled to receive an eighth, because they must be appointed by the ruler/party in charge.
Therefore, if he(proxy) wants to take anything ,then he must seek the permission of the donors. If he doesn`t , then he has betrayed the trust of God and has succumbed to the evil suggestions of the devil; therefore, he should make repentance and seek forgiveness.
Resolution No.(202) by the Board of Iftaa`, Research and Islamic Studies states that it is impermissible for administrators to take any percentage from the Zakaah funds and the same ruling applies to charity(Sadqa).
In conclusion, it is impermissible for the above woman to take from the donations, except after securing the permission of the donors. However, it is permissible for her to give a portion to her married son if he was poor or needy, provided that she isn`t biased for him. And Allah knows best.