The mold in your photo, such as the dark mold on wood framing in what looks like a ceiling space, is almost certainly not the mold problem in this home as it's almost certainly a cosmetic mold such as those discussed above on this page - one can see that by the mold growth pattern ...
Rag furnish is preferred, but there may also be used asbestos, cotton linters, and other long fibers commonly used in the manufacture of felt as a supporting layer in flooring materials. ... The filler may include a preponderant portion by volume of fibrous filler such as wood flour, ...