Bankruptcy Law Questions? Ask a Bankruptcy Lawyer.
Since she has filed, your grandmother is protected from creditors under the automatic stay provisions of Section 362 of the Bankruptcy Code. This means no creditor can make advances against her while in bankruptcy UNLESS the creditor files a motion for relief from the automatic stay and get permission from the court to proceed with the collection/foreclosure.
Thus, she has time. Once the creditor files the motion to lift the stay, the creditor will still have to get an order lifting the stay. Once it has this, it must then begin the foreclosure process. This process takes 60-90 days to get to the foreclosure sale.
So long as your grandmother is out by the date of the sale (which she'll have notice of), she'll be fine.