Federal: 1040NR but depends very much on the number of days she has spent in the US during the year; dual status return might also apply under some circumstances.

State/Local: unless there is no income tax for the state, she will likely have to file a non-resident state (and local, if applicable) return where she worked.

To prevent double-taxing, Canada and US has reciprocity agreements so the taxes paid in the US can be claimed on the Canadian return.

Depending on any other situations, there are additional factors to consider. I’d advise your friend and his spouse seek professionals to make sure everything is in compliance, as far as the filing requirements are concerned.