Is it permissible for a mother to take her daughter's money without her knowledge to use it for the needy, with the intention of returning it after receiving zakat funds from her other children?

A mother is not entitled to take her daughter's money without her knowledge to distribute it, as this is an encroachment upon the property of others. What the mother did is incorrect, and she must return what she took or seek her daughter's forgiveness for it.

As for zakat money, if the mother was appointed as an agent to disburse it, she should distribute it to those who are eligible. However, distributing it before being appointed as an agent with the intention of it being zakat is not sufficient, because intention is a condition for fulfilling zakat. If the mother distributed the money with the intention of it being zakat on behalf of its owners before they asked her to do so, it is not sufficient as zakat due to the absence of their intention.