Will my husband's income be lawful, given that he works as a taxi driver in Canada, transporting customers to and from bars and nightclubs?

It is forbidden to go to taverns and nightclubs that involve sin. It is also not permissible to assist anyone in doing so, whether by transporting them for free or for a fee, as this constitutes aiding in disobedience. Allah Almighty says: (And cooperate in righteousness and piety, but do not cooperate in sin and aggression). If the husband knows that the passenger intends to go to a forbidden place, it is not permissible for him to transport them. Nor should he wait for those coming out of these places, unless the passenger will be going to their home or a permissible place, in which case it is permissible to transport them.