Maybe You are right.Nirvana has a few bass lines that could teach you stuff about outlining the chord notes or walking. "Lounge Act" and "Lithium" come to mind. But the reason most of their songs are good for a beginner is precisely because they're simple. Walk before you run, etc. I think even "Smells Like Teen Spirit" would be fairly challenging for her at this point. She doesn't have much finger speed or strength.