Many people freak out when they see that black stuff on walls, etc. I think their first impression is "dirty". Importantly Mold and mildew issues should be inspected for the source of the problem, not just to look for a cover up. 

Ok, let's just say you actively took care of that but want to clean up what's there.

Bleach mixtures tend to make the mold spores jump to another spot nearby therefore really not "killing" the mold just moving it to grow in another location.

This mixture can kill mold and help with that mildewy smell.

1 cup of (cheap) vodka

1 cup of distilled water

10 drops of lavender essential oil

10 drops of lemon essential oil

Mix together in a spray bottle and use it to clean items such as a refrigerator, bathtub, shower, toilet area, garage, basement, etc. wipe or rinse afterward.