Which electron configuration represents an element with the highest first ionization energy?

Helium wins in this category: $1 {s}^{2}$
This means that the electron in the lowest energy level within its atom would require the most energy to ionize. While both hydrogen and helium have a $1 s$ electron as the outermost electron, helium requires much more energy to ionize because of the double charge on its nucleus (compared to hydrogen).