Hi
Thank you for your replies. By what you have said, I guess my conclusion is that without the PRC, which takes 6 weeks (is there any way to speed that up?), or a visitor visa, she cannot enter the US and return to Canada. I guess she will have to find housing in Canada right away. Thank you for your help.
1. No it can't be sped up, takes 30 days and she needs a Canadian address for it to be delivered.
2. Even with the PR card, she still will need a US visitor visa to enter the US.
PMM