what do you mean "she already returned the property". You can't unsteal something.
the "reasonable expectation of privacy" is not the issue. It is simply if a warrant is required or not.
As to exigency; if they believed a partner in crime was able to escape due to the delay required to obtain a warrant, they may be able to make such a claim. Not sure if that would be enough to justify the search but it might if they could defend the action itself as having some value. I don't see how it would but I don't always win my arguments.
so, the question is; what does she want to do about it?

