If it is columnaris and it's that bad, the fish is going to die. It's a very fast acting bacterial infection and once the white stuff starts showing, if immediate treatment isn't available, well, it's not good news. I lost over 20 fish to it in 5 days back in September. If it is in fact columnaris, some things that can be done is add salt to the tank and reduce the temp. If your friend has or can get meds, I'd do Kanamycin or Maracyn and Maracyn-Two simultaneously. One takes care of gram + and the other gram - bacteria. That way in case it isn't columnaris which is gram -, it will take care of whatever else it maybe, if it's bacterial. It would be kinda like a broad spectrum antibiotic. A bath of potassium permangenate or Methylene blue may also help.
Also, depending on the tank size, I'd move the fish to a smaller QT tank for ease of treatment. Your friend also needs to make sure the water is very clean and well oxygenated. Columnaris likes dirty water and low O2