Is it permissible for my husband to combine the Maghrib and Isha prayers upon returning home after his night shift at a hotel where there is no place to pray, knowing that he prays after returning home to feel a sense of devotion?

It is not permissible to work in a hotel where immoral acts are committed, or where alcoholic beverages are served, or where licentious parties are held. This is because it constitutes aiding in sin and condoning evil. There are two scenarios for income from prohibited work: The first is when one directly engages in the prohibited work himself, in which case the income is forbidden to him and he must dispose of it for charitable causes. The second is when one does not directly engage in the prohibited work, in which case he is sinful for being present in places of evil, but there is no harm in him benefiting from the income; however, he must leave this work.

As for delaying prayer beyond its prescribed time, it is a major sin, and work is not a legitimate excuse for it. Your husband must perform the prayer at its due time. If he cannot perform congregational prayer in the mosque or at his workplace, he must leave this job and seek another, because congregational prayer in the mosque is obligatory for men unless there is a legitimate excuse for not attending.