Buried in a housing law signed this week by President Barack Obama are protections that will help thousands of renters stay in their homes — at least for awhile — after their landlord has been foreclosed on.

The law allows tenants to remain in their foreclosed rentals through the end of their lease and then 90 days after that before being forced to vacate by the lender. Renters without leases will have 90 days, a significant improvement over what most received before: almost no notice at all.
http://www.msnbc.msn.com/id/30891380/

If she doesn't have a lease, I'm pretty sure the 90 day period starts from the day that the lender informs her that the house is in foreclosure.