I always understood Trant to be an English surname but here's something I saw on the web. Perhaps it is wishful thinking but it is a nice story
The name Trant doesn't sound very 'Irish" because it's originally of Danish origin. Legend has it two brothers from Denmark, John and Phillip Trant were mercenaries (and sons of a Danish chieftain) hired by Strongbow in the 1100's to subdue the Irish rebels in the west. The two brothers liked it in Ireland ...so much they managed to stay on. CahirTrant in Ventry near Dingle is their original homestead.