A song that I do that is kinda modern is "hotel yorba" by the white stripes, G C D all the way thru, very catchy tune, easy lyrics. I am sure she could pick this one up if she likes it enough.
also another easy one but it has Am F G C for most of it and very repetitive is " otherside" by red hot chili peppers, it does go into Em and C.
Hmmm, although I am not too sure of the chords but that ronan keeton ( or however you spell his name) he has a few very easy songs.
and one more from the top of my head the thrills song " dont look back into the sun" G D Em D C all the way thru.
hope this helps ye
Ken