All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad, is His slave and Messenger.
If the money that the husband gave to his wife was an allowance for herself and her children, then he has no right to ask her about the manner she disposes of it unless he notices some misuse on her part in this regard, incurring harm on herself or her children. This is because when a husband gives his wife an allowance to provide for herself, it becomes her personal property and, accordingly, she is entitled to dispose of it as she wishes provided that no harm is incurred on herself as a result. Ibn Qudaamah, may Allaah have mercy upon him, said in his book Al-Kaafi: “If he (i.e. the husband) gives her an allowance, she is entitled to dispose of it as she wishes, by sale, spending in charity and the like, because it becomes her property and therefore it is permissible for her to dispose of it freely just like her Bride's money, provided that it would not incur harm on her body and result in undermining his right to sexual enjoyment with her. In this case, the allowance is not considered her property because it would result in undermining his right.” [End of quote]
As for the money he gives her to provide for her child, it is considered a trust in her possession. This is why the Prophet authorized Hind, the wife of Abu Sufyaan, to take from his money what sufficed her and her child because he did not provide for them, as narrated in the Hadeeth cited in Saheeh Al-Bukhaari. Al-Haafith Ibn Hajar said in Al-Fat-h: “It (the Hadeeth) serves as evidence proving that there is a basis in Sharee‘ah for allowing a woman to assume responsibility over her children and provide for them.” [End of quote]
Allah Knows best.