What is the religious ruling on a wife taking off her niqab and adhering to it based on her husband's request to emigrate to Canada?

Emigration to the lands of the disbelievers is disliked for whoever is able to establish the rituals of his religion, and it is forbidden for whoever is unable to do so.

As for uncovering the face and hands out of fear of harm or out of necessity, there is no impediment to it.