I'm sorry to hear that your sister's house is foreclosed on.
Your sister's best bet is to look for a rescue organization in her area. PetFinder is usually touted for looking for animals but doing a search with her zip code can also bring up the names of shelters and organizations in her area.
Pet Harbor is another good site for searching for shelters/agencies:
http://www.petharbor.com/WelcomeFrameSet.htm
A "no kill" shelter may not PTS any animals on that premises but sometimes they will swap animals with other shelters who do PTS animals after a set amount of time (surrender/stray holds can vary from 3-7 days, depends on where you are and the agency itself).
On the bright side, smaller dogs are often easier for rescues to find foster homes for and also get adopted quicker out of shelters. I hope for the best outcome for your sister and her pups.