Ruhengeri, commonly known as Musanze, is generally considered safe even for solo female travelers. The local people are friendly and incidents of crime are relatively low. However, like any other destination, it's always advisable to take standard travel precautions such as not wandering off alone late at night and keeping your belongings secure at all times. Local authorities are typically responsive and most areas are well-policed, fostering an environment of safety. The greatest concern could be traffic safety, particularly if you're not used to the local driving norms.