Make sure she packs light clothing and a very high SPF sunscreen. 50 or above will be fine. Durban can get very hot and insanely humid! She should have one heavy jacket and a couple of sweaters for the cooler winter months though.
If she's bringing over any electronic/expensive items she should keep these out of sight as far as possible and always store these in a safe place, preferably locked. On campus theft can be a real issue.
Walking around in some areas of Dbn while wearing expensive jewellery/watches etc or carrying an obviously expensive phone is not recommended. If she drives, all such things should be locked in the boot and not left on seats in plain view. She should not engage with panhandlers/beggars, even if this means that she has to be a bit brusque. In a car, windows up or barely cracked, and ALL of the car doors locked. No exceptions.
She should be wary about accepting help from anyone at an ATM, there have been cases of 'security guards' helping people out of their money at ATMs which they themselves have disabled in some way. The vast majority of security people are fine, just make sure that they're legit, and if she's in a situation, she should not hesitate to approach one. Usually they have little kiosks, reflective or orange vests over a dark uniform. The company they work for should be clearly marked on their uniform.
If she stays away from the bad elements (drug users etc) she should be fine. A situation can get sticky very quickly if you're under the influence, and you don't know where you are or how to get help. Be very careful who you associate with! It will probably be very tempting to hang out with the locals and enjoy the 'real' and gritty South Africa, but it is unwise. By all means enjoy Durbanites, they are awesome. If someone offers you a personal tour in their vehicle of the sugar cane fields, for example, kindly decline.
In essence, be careful and aware and watch who you associate with. You'll have a great time. Durban is a wonderful and beautiful city and crime isn't an issue if you make sure to take adequate precautions.
Welcome and all of the best with your studies. : - )
P.S: I'm female and have lived in Durbs basically my whole life. If you want my number I can PM it to you for her to keep in case she needs advice/help or whatever.