Mthembu embraced his son after becoming the first South African runner to win two titles since Bruce Fordyce in 1990.
Herron was the world 50-kilometre and 100-kilometre champion in 2015, but says winning the Comrades has been a dream since she first started reading about the race in 1995.
Herron did all the hard work from Pinetown when she took the lead, only for her to think she had won by just entering the Scottsville Race Course.
With more than a four-minute gap over second-place, 2017 Comrades Marathon champion Camille Herron stopped short of the finish line thinking the race was over.
Camille Herron from the United States of America was closely followed by Russia's Alexandra Morozova at 06:31:45 and the first South African lady to complete the race came in third as Charne Bosman made it in 06:39:51.More news: Illinois' budget battle moves into overtime
More news: Four countries cut links with Qatar over 'terrorism' support
More news: Dr. Beach names Florida's Siesta Beach best beach in US
Herron, who broke down in tears of joy while also almost failing to finish the race, said she wanted to match her compatriot's efforts.
Athletes belonging to the Orlando Athletics Club are ready to take on one of the biggest road marathon in the world, the Comrades Marathon.
It was too late at that point and the Oklahoma-born trail specialist made up for her 2015 disappointment when sickness prevented her from finishing.
Mthembu was followed by Zimbabwean Hatiwande Nyamande who finished second in 5:38:46.
Although he set an strong pace throughout, Mthembu was unable to beat the "up" run record of 5:24:49 which was set in 2008 by Russian, Leonid Shvetsov.