Oh my gosh, Debby, she is so cute. Maybe she got scared and ran out when some trick or treaters came to her door. I agree with Steph about calling local shelters to see if anyone called reporting her missing. Also, something I learned about when Kay found the Rottie (I forget her name). You can go online and register your dog as missing in your area through Petfinder. You may want to see if they did that as well. I have a feeling that you will find her owners soon. And she may be chipped.
I think it is wonderful of you, Maggy, Payton, and Sammy to share you warm, dry house with this little girl tonight.