It was a kind thought to bring cat nip, but it usually only exasperates how the cat feels....a happy kitty more relaxed, a nervous or mad kitty more aggravated. But you meant well, sorry it didn't work out.

Personally I do not recommend taking that cat to the hospital, it would be even more scared and mad and lash out. Would not be good.

Seems like the man loves it, could the cat be being abused when his wife comes? Or is its personality just like that all the time. I can see why they wouldn't want it if it was. Could be dangerous to their other pets or kids. Strange it acts this way though. Something had to have happened to it. It's probably afraid and it lashes out rather than run away.

I don't know how much time you have to give it, but maybe sit in a chair, turn on the tv, use the laser light occasionally, keep treats with you that you can offer it and give her one now and then if she comes near. Talk gently and let her come to you first. This is going to take some time but she may come around with patience. Of course all the good you do may just be wiped out if the wife does differently when she comes. This will take consistency and a lot of time.

Maybe take a pic in your phone and print it for the man to see his cat. He'll be happy for that.

I don't know what else to say.. sad situation but I hope something gets better.