You were on the right track but catnip does make some cats more aggressive. She probably fell asleep right after you left though! It does sound like she is scared and maybe a bit protective of her territory. I would suggest a taking a toy like Da Bird or something with a long stick and feather type that you can get her to chase. If she likes the laser pointer, she will probably chase something she can grab. Mine only go so long with the dot until they want to actually catch something.

Also, with the feeding part, are you giving any canned food and if not, will they let you? You can feed canned close to you, so she can get used to you more and associate you as the person that gives her good things. As stated before, the more you can just sit and let her come to you, the better. Make sure you are relaxed and maybe read a book or watch tv and don't pay attention to her. She should, if not come around, at least not attack you when you try to leave.

One last thing, maybe a short video of her playing would lift her owner's spirits. If you have a smart phone or maybe he has one you could try that. She definitely wouldn't be herself if taken to the hospital.