I guess you’re not going now, right? (This response was written during the 2020 pandemic.)
In normal times, when the border is open, she needs a passport. There are multiple options to speed up the process, but they cost more the faster you want it. The important this is that all urgent passport applications must be applied for in person at a Passport Canada office. If she cannot do that, she will have to apply the normal way (by mail) which takes 20 calendar days, not including mailing time.