If you setup sshd server and have it running, then as long as the port 22 is open to the internet then you should be able to use a command like this to run X apps from that machine and have it displayed on yours.
ssh -Y
username@xxx.xxx.xxx.xxx
replace username with the name of a user on the remote machine except root.
replace xxx.xxx.xxx.xxx with the ip of the machine seen from the internet.
The -Y allows an X app to run on the ssh connection if the sshd server allows this. Now you will have a terminal session so then you can run the remote users firefox, nautilus,konquorer, or any number of other web browser capable software. The enter the 127.0.0.1:631 to make the connection to the cups server.
Some of this depends on the internet setup. If broadband and have a router after the modem and before the machine then it needs to have a port forward setup to forward external IP port 22 to internal IP of the machine to work on. Also some providers block common ports like this so they can charge more to allow you to run a server. So if this is the case then you called connect to the external IP plus say port 10100 as example. Then the router forwards this connection to the internal IP at port 22 when defined.
Another way is setup VNC and use that. Or one can even VNC over SSH conection for secure encrytion.
Now depending on the distro and maybe the gui there may be a remote control tool like KRCD and a few others. Again depends on the system. If broadband and firewall router involved then again port forward may have to take place on either the remote of local end. Depending on which tool is used and who estianates the connection.
The easiest is to do the same thing on your machine while talking your mom through the process.
Brian