Head tilt is usually caused by an inner ear infection or the e. cuniculi parasite, though there are other less common causes such as head/neck trauma, stroke, cancer, etc. If EC is the cause, though it can be contagious to other rabbits, the majority of rabbits are already asymptomatic carriers, meaning that they carry the parasite but it doesn't cause disease. If you are concerned still, research found that treating exposed rabbits with a 9 day course of fenbendazole(liquid panacur or safeguard) 20mg/kg once a day, can help prevent contraction of the parasite. You can read about it here.
http://www.medirabbit.com/EN/Neurology/Paper/fenbendazole.pdf
If it's an inner ear infection then your rabbit will need to be on an extended course of a rabbit safe antibiotic(usually 4-6 weeks or longer). Meloxicam is usually also prescribed for both EC or an ear infection, to help bring down inflammation that can lead to permanent cell damage and increased symptoms. So it's an important part of the treatment to make sure it's included. If the vet can't determine which disease is the cause of the head tilt, they will often treat the rabbit for the possibility of both illnesses with fenbendazole, an antibiotic(often baytril), and meloxicam.
http://www.medirabbit.com/EN/Neurology/Otit/otitis.htm
You also need to ensure your rabbit continues to be able to eat and drink well. If not, syringe feeding becomes necessary by using a recovery food mix like Oxbow critical care mix. This link has info on the some special care for buns with head tilt issues.
http://www.disabledrabbits.com/head-tilt.html
I should also mention that the head tilt could be from previous illness/injury in the past, and your rabbit was left with permanent damage and a remaining tilt. So she may not still be ill but will just have the tilt for the remainder of her life. Which is ok. There are rabbits that go on to live perfectly happy lives with their remaining disability.