My husband took an at home urine druge test. He failed for cocaine and the only thing he does is drink energy drinks such as monster and nos. could those have caused his false positive on the test for cocaine?

Yes it could... leastwise energy drinks have been known to cause false positives for amphetamines and cocaine on immunoassay (IA) tests... that would be the type used at home.

IAs have a high rate of false positives anyway so it isn't possible to pinpoint the cause but energy drinks are suspect.