Yes, they can decline to show the property. Once there is an offer in place the seller may have directed them to not show the property anymore. It robably still shows as being available on public websites, but shows as having an offer in MLS.
The term "pending bank approval" indicates to me that it is either a short sale or a foreclosure. The bank may very well have directed the broker to suspend showings once the offer was in hand.
The best idea for you and your husband is to hire the services of an agent to represent your interests in the home purchase. This requires a contract, but the service is of no charge to the buyer since the agent is paid from the seller's proceeds.
First Weber Group