Um I have the same thing LOL my moms laptop is on XP and uses my printer ha ha. Easy fix man.
Setup the homegroup on your computer, make it to share printer, etc. Then in homegroup settings, disable 'password protected sharing'.
Just double check the workgroups as well, to make sure they're both on the same one.
Then go into Network and see if you can see your moms laptop appear on their. Same on her laptop. If that works, then just double check the printers share name and yea
Just ask her again if you need any more help!