Must the wife remove her niqab—which she wore after agreeing with her husband—because of the refusal of the husband's family and the husband's threat to end the marriage if she does not remove it?

It is not permissible for a husband to prevent his wife from wearing the hijab, nor does he have any right whatsoever to do so. On the contrary, it is obligatory for him to encourage her to wear it. It is also not permissible for his wife to obey him in this matter, because there is no obedience to a created being in disobedience to the Creator, even if it leads to separation. This is based on the Prophet Muhammad’s (peace be upon him) saying: “Indeed, the conditions most worthy of fulfillment are those by which you make intimacy lawful.”