Can we drop out of this home sale deal without penalty?

We are presently in contract to sell our house. The Buyers have put their 10% down in escrow. Contracts were signed on Oct. 17th. All documentation is in. Contract reads closing to be on or about November 15th. We realize the buyers have till Dec. 15th to close or lose their down payment. The problem is we believe they cannot get their mortgage now. Their bank apparently will not approve the amount they were originally told and we just now found this out. It's already 30 days since contracts were signed. The contract states that if either party wishes to pull out after thirty days the funds will go back to the buyer. It says nothing about whether they will penalize the seller. We are afraid that after another month has gone by they still won't be able to get their mortgage and we will have wasted 2 months of our time and possibly we may have gotten other offers which might even be better. Aside from that if we initiated the cancellation of the deal wil we be penalized?