She may have been abused by men in the past, but you have another day or so with her, so don't give up yet! It took a couple weeks for a friend of mine's pound-pup to not growl at her husband when he came home, but now he knows Dennis won't beat him, he loves him too. In any case, be careful and make sure any men in the house don't make any sudden moves near her, and that will help. Have your brother offer her a treat, very calmly. He should just hold still with the treat and call her over, if she won't come to him, he can put it on the floor in front of him, just so she begins to associate boys with good things happening.