I assume that your grandaughter is the owner of the property that was foreclosed. Assuming so, a three day notice must first be served after the foreclosure. At the end of the expiration of the 3 days, if she has not moved, an unlawful detainer law suit must be filed. If the case were to go all the way to trial, she should have at least 45 days. However, there are ways of getting extended time from the court to move.
As a practical matter, most banks do not start eviction actions immediately after foreclosure these days. When they are ready to deal with possession of the property, they are likely to offer your daughter a "keys for cash" deal in which they will agree to pay her to move voluntarily.
If your grandaughter is a tenant, they must honor any existing lease. If there is no lease, the bank must give her a minimum of 90 days notice to move. If she doesn't move, the unlawful detainer process will start as decribed above. Again, they would be likely to offer her a "keys for cash" deal.
Jeffery P. Woo, Esq.
Sedgwick, Detert, Moran & Arnold LLP
Complex Rental Property Group