From a straight compliance standpoint, flood insurance is required when a bank makes, increases, renews or extends a loan for a property that is located within a flood zone.
Since the property was aquired through foreclosure, I don't believe there is a regulatory mandate that the bank have flood insurance on the property. I may be wrong, but I'm assuming that title was transfered to the bank and the bank did not have to have a loan to "purchase" the foreclosed property.
From a Saftey and Soundness standpoint, your bank may want to elect to have flood insurance on the property that was aquired through the foreclosure process.
Finally, if your bank elects to have flood insurance on the property, you may want to look at the replacement cost of the property instead of an appraised value to determine how much flood insurance the bank should purchase.