Door Crashing
This sounds DEFINITELY like something that a dog who is in new surroundings would do.
Your friend should take Molly out of that shelter and get her into one that is no-kill, ASAP. I have serious questions about a "shelter" that decides to put a dog down based on what ONE person who has had her for two days says - especially if she has never been a behavior problem previously, and she's not a danger to others.
Whatever breed Molly is, have your friend call a breed rescue. They will help.