My advice is tell her to try and bond with her bunny, like laying on the floor and letting the bunny come to her, or maybe suggest taking the bunny for a car ride and the owner just comfort the bunny (obviously with someone else driving), most likely the best way for those hormones to go down is going to be spaying the bunny, my guess is it hit maturity and is having the hormones. I would try in anyway to help the owner because around 6 months of age a lot of bunnies get dumped because people don't realize bunnies hit their maturity and gain aggressive tendencies, now not all bunnies get aggressive but its better to get the spayed than later! I hope my suggestions help!
Lastly, the bunny could be aggressive due to the housing situation, is there any other animals? Dogs and many other animals can make bunnies be fearful leading to aggression. Are they indoors, outdoors? In a cage, xpen, hutch, free roaming? Are there kids in the house? Loud sounds? All of these factors can also lead to being aggressive. SO I would just ask the owner some of these questions and see if there's a solution! Like if it's cage aggression maybe they try a xpen if they can't free roam! If outdoors, maybe just try indoors, something may be making them feel like prey outside!
I really hope this helps I would just ask them some of these questions and give them some tips to help them!