Does a husband's prevention of his wife from enjoying the wealth with which Allah has blessed him, and his saving it for difficult times, constitute "withholding al-Ma'un" as mentioned in the Qur'an, or is it his right since he is the earner of the money?

If a husband provides his wife and children with the obligatory maintenance, pays Zakat, and does not withhold what is customarily lent, then he is not among those who withhold al-ma'un. It is permissible for him to save money after providing the obligatory maintenance. In case of a dispute over maintenance, the matter should be referred to the Sharia court.