If she’s getting the “Not Enough Space…” error message, she won’t be able to get to the Settings menu to run the Format command.
I’d suggest 1.) Trying different USB ports to get a data connection. Then you can simply remove a few files to give it the ‘breathing room’ it needs when operating in MTP mode. Or if that doesn’t work 2.) Putting the HOLD switch on & holding the center button down (with the player off) while you plug the cable into the device (cable already plugged into the computer at the other end). This will force an MSC connection. The song files, being sync’d in MTP mode will not be visible, but you should be able to right-click on the player in Windows Explorer and use the Format function there. Don’t use the Quick Format option. If the player is 2GB, use FAT; if larger use FAT32.
As mentioned, this will erase all user-added content so you’ll have to re-load everything (not firmware). If this works, go ahead and use the on-board Format funtion on the player afterwards. This will optimize the memory cluster allocations.
If you’re dead-set on syncing, then after all this you’ll have to remember to go back into the Settings menu and switch it back to MTP mode. Under no circumstances should you use the Auto Defect settinig. Now you can start filling 'er up again.