I'm not sure this meets the definition of scholarship/fellowship from Section 117, but the idea is the same.  She is not a self-employed honorarium collector.  I'll give you a 50% chance of convincing some clerk at the Service Center that this income was already reported, and it's not SE income.  Make sure when you reply to the CP-2000 that you ask for the case to be sent to Appeals if your explanation is not accepted.  Not that correspondence exam will pay any attention to the request, but it helps if you want legal help with a Tax Court petition later.  

As far as I have been able to figure out, the minimum for a CP-2000 to be issued is $500 difference in tax.  How much do they hope to get from this?  No other issues on the return?  Maybe $300 for income tax, $200 for SE tax and $250 for reduced premium tax credit?  Was this a joint return?