They issued her a letter confirming she was OK to drive
They wouldn't even do that with me.
I rang the DVLA naively expectcing advice when I queried whether I have to declare ocular migraines, and got my licence confiscated on the spot by a kid in the call centre who said "what's a migraine". I then got a letter telling me to return my licence, and that it was no longer legal to drive. After I sent it back, they kept referring to the letter as the "options" letter, and telling me that my licence hadn't been cancelled on the computer, but refusing to confirm that in writing.
The only reason I got invovled in the first place was that the GP had refused to advise, telling me to ask the DVLA, and adding "it's not my job to give medical opinions". That was the start of months of playing pig in the middle, because the DVLA kept telling me I could have my licence back as soon as the GP said it was safe, and the GP refused to make a decision, ignoring their letters asking for one.
When I needed to know if I was safe to drive with arrhythmia I asked the Dr at the hospital, and he visibly squirmed like a worm on a hook, then avoided the question. Having learnt my lesson from last time, I tried printing the form off the DVLA website, and posting it to them, and this time it was fine. No letter telling me to surrender my licence, so I kept it until I got a letter telling me I could keep it.
It seems to me that the DVLA are the one and only thing that doctors are frightened of.