If you're still having problems with the missing images-
I copied everything from ..\Babysitter-019b-win\Babysitter-0.1.9b.-win\game\images\backgrounds into the ..\Babysitter-020-win\Babysitter-0.2.0.-win\game\images\backgrounds folder. I told Windows to skip the replacing of image files or the RoomButtons folder that are already there and that seemed to do the trick. Basically, I just copied over the image files that are present in 0.19 but missing in 0.20.
I haven't played through all paths yet so I can't be sure that everything was fixed but all of the Ren'Py missing image file errors on the two paths that I tested are gone. I did encounter an issue of one image with a file present that displayed a brown screen without a Ren'Py error and I'm not sure what's up with that. Still though, the update is actually fucking playable now.