The sentence "She is one of those rare individuals who goes out of her way to help others" exhibits a subject-verb agreement error. The relative pronoun "who" refers to the plural noun phrase "those rare individuals." Consequently, the verb must also be plural. The correct phrasing is "who go out of their way" to ensure number agreement. The corrected sentence is:
She is one of those rare individuals who go out of their way to help others.