documentclass{article}
usepackage{enumitem}
begin{document}
begin{enumerate}[label=(roman*)]
itemlabel{A} First
itemlabel{B} Second
itemlabel{C} Want to have (ii') here.
itemlabel{D} Fourth
end{enumerate}
Let's reference them: ref{A}, ref{B}, ref{C} (want to have (ii') also here), and ref{D}.
end{document}