Yes. However, if she leaves and needs to return via a commercial carrier, she would need her PR Card (or a PRTD) to board a flight as she would no longer be a `visitor' to Canada.
I've heard of at least a few instances where the mailing of the PR Card to an overseas destination may be intercepted by the Customs agent, if it's something that cannot be imported into that country. I think it's rare, but it has happened. The PR Card has an RFID chip which can be detected.