So, you want to move folders that have mp3's in them? Check the sticky article at the top of this forum on how to get Hazel to go into the subfolders.
From there, create another rule to match the mp3 files themselves. Now, here's the tricky part. Use the script here:
viewtopic.php?p=1545#p1545What that does is tell Hazel to use the parent folder in subsequent actions in that rule. So, if you do a move action after that, it will move the parent folder and not the file itself.
Give that a shot and report back if you are having problems with specific parts.