"Been" in option B is the correct answer as 'been' is used to refer to completed visits. As the hair looks nice, the visit must be completed. 
"Gone" in option A is incorrect as it is used to indicate the visit which is not complete.
"Was" in option C is incorrect as it does not make sense to say 'she has just was'.
"Went" in option D is incorrect as 'went' is the past tense of 'go' Here, we need the past participle form and not the past tense. 
Thus, option B is the correct answer.