You have my prayers because I know just how you feel. It happened to us with one of our cats and he was gone for three days. What the vet told us was sometimes they might go in someones garage and hide and then the door gets shut. In your case that is probably not what happened but cats have wonderful instincts and your little gal should be able to take care of herself.
It sounds like you're following some good advice with all the steps you're taking. She still might be spooked by the guy that came by yesterday and is wondering if it's safe to come home. As close as our cat Junior is to my husband he hid from him for almost a day after my husband accidently stepped on his tail.