I'm not sure there's a plant question here, anyway, If the pipes were wrapped with insulation that will stop the sweating of the pipes, unless it was a leak. Not sure where you live, but in the winter here the air is very dry just because cold air can't hold as much moisture. When heated it becomes even dryer. There are paints that contain a mildew retardant that can be used. I'd wash the bedding with a bit of bleach each time, and do it often. If there are plants involved and you want a humid area for them I'd find a different room. You can always spray them with water from a spray bottle a couple of times a day in the winter. I don't think any room that is so damp that mildew grows would need any further humidity for plants or people.
