Is it permissible to give money in cash to a girl for whom it was collected for her marriage and to buy furniture, but her marriage was delayed and she is now in dire need of the money, and is the one who collected the money sinful for that?

The questioner should seek permission from the donors and inform them of the true situation. If they permit giving the amount in cash, there is no harm. If they do not permit it, then he must abide by their condition, because the disposition of donations and endowments is according to the condition of the donor or endower. If they refuse to give it in cash, then he should strive to meet her need through charitable donations or Zakat funds. If the matter becomes difficult and he finds no way to meet her need except through this money, or if she has an urgent need, then there is no harm in giving her only what meets her need from these funds, as long as this money was collected for her on the basis that she is poor and cannot find anyone to prepare her.