For hen, you can rule out buttercup and penedesencas. They both have have white ear lobes. Sexlinks can vary so much in coloration, that is a possibillity.
does the hen lay yet? if it starts laying colored eggs, like blue or green, then its definatly an Easter Egger or an Ameracauna. I have two much lighter, but my grandma has very dark ones that look a lot like that.