Sounds like it happened due to moisture and not proper gutter drainage.

Moisture level in the crawling area is 20%There is a crack on the ceiling but there is no crack along walls.

However they said that the tenant's furniture was in the way and preventing them from completing work necessary to eliminate moisture.

Several in the thread have pointed out that they didn't think the romex alone could be causing the problem, but my (admittedly uneducated) guess of what is happening is that the line has already degraded and is exposed to the earth, and occasional moisture which is causing the issues.I contacted the sellers construction manager today (he did some other work on our punch list and was an all around good guy), and waiting to hear back from them.

Michael- " The moisture content of the stucco was tested on the north side of the house with a non invasive moisture meter.

It is likely caused by condensation resulting in moisture.

Depends if you did that kind of stuff before.My biggest issue would be the roof "wave", that's a marker for moisture invasion and more. 

I had a contractor come by and he said there are cracks on the walls and a lot of moisture, most likely floor cracks as well.

All exterior outlets and outlets within six feet of a water source should be GFCI protected.The bathroom exhaust fan was loud and should be serviced or replaced soon.Alarms and DetectorsThere were no carbon monoxide detectors in the home and one should be installed within 15 feet of every bedroom.InteriorSeveral windows were quite weathered and wornThe glazing was cracking om most windowsSeveral windows had weak or failing sash supportsThe left side rear window did not close properlyThere were previous moisture stains on the right rear bedroom ceiling that were dry at time of inspection, but should be monitored for action.

It would be a good idea to have an architect review the mold condition and see to what extent the damage is and where the moisture penetration is coming from.