How do I hide the parent folder of the user home folders in File Sharing?
Mac is mostly unix under the hood.  Try setting the permissions of the /Users folder to everyone only execute.  

E.g. Currently:

bash-3.2# ls -ld /Volumes/Users
drwxrwxrwx  10 root  admin  510 23 May  2012 /Volumes/Users

bash-3.2# chmod o-rw /Volumes/Users

bash-3.2# ls -ld /Volumes/Users
drwxrwx--x  10 root  admin  510 23 May  2012 /Volumes/Users

OS X has addition access control tricks, so this may not work.