"Could box 2b be checked since she made a qualified charitable distribution?"
That has nothing to do with a QCD. Box 2b is required to be marked on any Form 1099-R with code 1, 2 or 7 in box 7 and the IRA/SEP/SIMPLE box marked because the payer has no way to know if you have basis in nondeductible traditional IRA contributions that would reduce the taxable amount, calculated on Form 8606 Part I. (Note that because QCDs can come only from otherwise taxable funds in the IRA, QCDs are not reported on Form 8606. When you indicate to TurboTax the amount of the QCD, TurboTax automatically excludes that amount from taxable income.)
