lonicera one of my friend's sons was in a flat with 17 at Warwick, and they split into two halves for second year flats. Might that be an option for the next year, 2 flats for 5 with 2 new people in each flat perhaps?
Ds1 has finally picked second year accommodation, the exact opposite of what I suggested, but he has found 6 other people for a seven person halls flat, none of whom he is sharing with atm, so hopefully they will all find a new life together!!! next year I mean...
The other good thing is that it is a university owned hall so if someone is deeply unhappy with the social group or discovers my ds's housekeeping flaws they can easily bail out, as it is easy to find new tenants, uni guarantees it. Ds said he wanted to be nearer clubs and shops and further from campus, and that he loved walking so much that early morning walks didn't bother him but walking back late at night did 
Luckily there are 6 people who appear to share his views.
Ursula your dd is so kind to support her friend, but you probably should remind her that it is not her responsibility to be worrying about the MH of her flatmate, and could be positively dangerous to take on that responsibility when she cannot give professional advice, know what best course of action is. GP, counselling, someone else should be alerted, or she should walk the friend to someone who can take note of this..and insist on someone else knowing how bad friend feels, who isn't a first year student. I can remember seeking advice from my peers in a difficult uni situation, not depression incidentally, and I so wish that I had thought to ask older wiser people rather than my kind friends, really with no experience how my peers were qualified to help me I do not know. But it is a trap we often fall into, even as 50 year olds.
Ds1 seems alright atm, fingers crossed.. Dd is having a few year 12 wobbles, and I've decided to start picking her up half way home, as possibly resilience is overrated and I cannot help her with her actual A levels, so maybe the driving will have to give. Ds2 also in Year 12, is now onto the classic 5 hours sleep, "cos I have to stay up all night to finish my class presentation which is due in and then get up at 7.30", which makes me very stressed, I practically forced him into his pj when he came home, although he said he wasn't in the slightest bit tired this afternoon. Ds1 blood curdling descriptions of late night essay crises and staggering to lectures on two hours sleep has made me hyper sensitive to it all, I just cannot bear any of them getting stressed and exhausted. However, ds2 doesn't seem to mind being tired, it doesn't worry him. He may be the perfect student in waiting.