When it comes to Medicine, which university is not actually particularly relevant, as the courses are all regulated (and you do know that the Russell Group was set up as a lobby group, named after the London Hotel where its representatives held their meetings?). If she is only interested in attending a Russell Group university to study Medicine, then firstly, she is restricting her options and secondly, does she actually want to be a doctor and to practise medicine, I.e. provide a vital service for other people who have very specific needs for professional assistance, or is she more interested in prestige...?
If the RG thing is the most important to her, then there are lots of other degrees available, which are easier to get into than Medicine and will give one the RG badge at the end.
Or is the school feeding them the line RG good, nowhere else worth bothering with, with no reference to individual courses?
If she gets herself over to The Student Room, there is a whole megathread set up to give advice on which medical schools it would be strategically best to apply to, given the aspiring applicant's specific set of achieved and predicted grades etc.
www.thestudentroom.co.uk/showthread.php?t=6679038
Unfortunately, some medical schools do 'score' GCSEs as well as A levels and the UCAT / BMAT score, so even multiple A*s at A level don't necessarily guarantee a high ranking, so it is worth looking very carefully at each one's methods and for that purpose, ignoring completely the 'group' that the medical school's university is part of.