I would suggest you log into gmail, go to contacts and make sure that all your contacts are all "cleaned up". Meaning no duplicates, no one she doesn't really want in there, etc. You could also create a group of just the contacts she wants and export only those. Then, on the menu bar towards the top under "more" you can export your contacts. Choose which contacts to export and then export to google csv. Then have her log into her gmail account online, go to contacts and click "more" and choose import. Then import that file.
Once she activates the Nexus and enters her google account info it should sync her contacts within a minute or two. If it doesn't sync within a few minutes of activating, she may need to go into menu > accounts & sync and make sure her google account is 'checked off' (sync symbol in green) and then click on the google account as well to go in and make sure that she has the desired services synced. I recommend only syncing features she actually needs to sync. For me that is contacts, calendar, browser and Music. Anything she doesn't use or need will simply waste battery trying to sync all the time. Google+ and photos seem to be big battery drains, so if she doesn't need those, disable the sync. Same thing with twitter and facebook. If you don't need constant updates, don't have them sync.
