Go into /home and issue
and look at the results, typically
drwxr-xr-x 2 user group ... <dirname>
First, remove world ('other') access
On RH (& likely RH derived) each user defaults to having their own private group, so that's as far as you need to go.
On a lot (most ?) *nix systems, users default to the same group unless otherwise specified, so remove group access