Firstly, my sympathies with your DD. I remember not getting the results I had been predicted and feeling like my world had fallen apart. I can't comment on current medicine but if you and feel she is capable of AAA and there are potential places available I think she should do what she wants.
We are going back a little way but in my case the school recommended a nearby private college, where I could do resits, I had achieved CDD (I had been ill and had my exams in isolation and there were issues with the physical exam papers and incorrect copies which just threw me and I never recovered my composure for the whole exam period, I knew I was capable of better and wanted better results on my CV). I did one term of lessons and then resat exams in two subjects in January, coming out with AB. With hindsight, I wish I'd sat the maths exam again in the summer because I was seven marks off an A, so I probably could have got there.
I couldn't do my chosen course with the initial results and I'm very glad that I made the effort to redo and improve, there was one other person from my sixth form at the same college who was doing medicine and had to improve his grades and he's gone on to be very successful as a medic so if you're dd is driven and wants to do it, support her, she should go for it.
Post-uni, my A-Level grades haven't mattered at all, but it mattered to me then to have an accurate record of what I was capable of achieving.