Your colleague might want to stop by the DMV/RMV and have a temporary license printed out. I've used those to rent a car from Hertz in the past without any problems. Otherwise, I've found Hertz to be somewhat strict (and reasonably so), and they won't allow the rental to stay in your colleague's name if only her husband has a license. If it comes down to it, the gold desk should be able to change the reservation to her husband's name however (and a smaller Hertz location at the Wynn in Las Vegas offered to do this for me in January when I could find my license, though I ultimately did).