I wouldn't leave a business card because of the possibility that the abusive husband might find it. If he's crazy enough to charge a bunch of police officers (and why the heck was he released so soon after that?), then I wouldn't want him knowing my name.

But I also wouldn't assume that the abused wife has family and/or friends who might help. Abusers often succeed in cutting the abused spouse off from family and friends, or they prey on people who lack support systems to begin with.

She knows where to find you and that you're concerned about her, and that most likely means a lot to her right now. Maybe you could check on her from time to time?