Answer

At first glance, it would seem forbidden because of “drying up the harvest” (in the Babylonian Talmud, Bava Batra 10b, this prohibition is brought so as not to grant them the reward of a commandment), and if it is public, it is also forbidden because of desecration of God’s name (Sanhedrin 26). However, there are quite a few grounds for leniency: whether it is also forbidden when this is done in an organized way; whether this counts as public for the individual recipient; and whether, once they have in any case already established a fund and I am only taking from it, there is any prohibition involved. And if they are not idol worshippers, and certainly if they are lovers of Israel, it seems logically that there is no prohibition in granting them merit. See Shulchan Arukh and the commentaries, Yoreh De’ah, section 254.
See several sources here: http://www.srugim.co.il/80377-%D7%A4%D7%A1%D7%A7-%D7%9E%D7%95%D7%AA%D7%A8-%D7%9C%D7%A7%D7%91%D7%9C-%D7%AA%D7%9E%D7%99%D7%9B%D7%94-%D7%9E%D7%A7%D7%A8%D7%A0%D7%95%D7%AA-%D7%A6%D7%93%D7%A7%D7%94-%D7%A9%D7%9C-%D7%A0%D7%95%D7%A6%D7%A8
Beyond that, I am uncomfortable forbidding needy people to use charity funds when I am not giving them another financial source in its place. If this were an outright prohibition, fine. But when there are grounds for leniency, then certainly this is a decision for each person to make for himself. In the Shulchan Arukh itself there, subsection 1, it is written that when one does not have enough to support himself, it is permitted privately.