Is It Permissible to Change a Charity Intention After Making a Promise to Allah?

Your vow was a conditional pledge that if your dua was fulfilled, you would give charity to poor children in Gaza, and since Allah accepted the dua, then according to the Hanafi school, the obligation of the vow is simply to give charity. Restricting it specifically to Gaza’s children is not strictly necessary; it may be given to poor people in general. Therefore, you may give half the amount to the children of Gaza and half to the poor single mother, since both are needy, and the vow will be fulfilled. However, as a precaution, giving priority to the original intended cause is better.