We used bleach to get rid of a mold problem in a closet in our house and it hasn't come back. We just used a bucket of bleach water and scrubbed and scrubbed until it was gone. There are still some stains on the walls, but it's not too bad. That would take care of the mold on hard surfaces, but I think it's harder to get rid of it on soft surfaces like your mattress. I have no idea how to get rid of that.

These days we make liberal use of a dehumidifier to keep the rooms from developing any new problems. We don't have central air conditioning, so summers can be bad, but the dehumidifier helps a lot. In the winter we always need to remember to open the closets and leave them open from time to time--they are uninsulated so when the dampness and coolness combine, we could develop new mold easily. Just keeping them open every once in a while seems to dry them out enough to prevent it.

Good luck!

Sarah