Hi there Steve!
If my son-in-law did that, well... Oh, never mind. You know!

First of all, glad you have the images saved to your computer! Personally, I would have reservations about trying to transfer them back to the xd card. You can always burn them into a cd or copy them to something like a zip drive instead.
If I understand you correctly, you renamed the images while still on the card...something else I would avoid in the future. Digital cameras have their own file and folder naming system. At the very least, if you want to try something like that, you should rename them in a similar fashion. But again, it's not something I recommend. I don't understand the technical aspects but, from everything I've heard and read, folks always run into trouble when renaming or deleting images, or formating the card via a computer.
The images may still be on the card however so you may wish to try some
rescue and recovery software. The software, in most cases, is very effective. We have a tutorial about it here:
http://www.digicamhelp.com/digital-photo-recovery-and-rescue/Whether you recover the images or not, you should format the memory card
in the camera. This will wipe everything off the card, and give you a clean "slate."
Hope it works for you so you stay in the good graces of your mom-in-law. Let us know how it goes.