E-pe-ink-ah appears to be for Ipįwįga, "Good Mouth Woman," or "Pretty Mouth Woman." This name is from I, "mouth"; pį, "good, pretty"; -wį-, a feminine gender infix; -ga, a definite article suffix used in personal names.
In an affidavit sworn on 20 Sept. 1838, "John Vunk, a white man, who being duly sworn according to Law doth say. That he is about 26 years old—That he was married in May 1836 to Heigh-noh, who was a full blood Winnebago woman, being the daughter of Wild Goose. and E-pe-ink-ah. That he has a son by his said wife, named john, who is now about twenty months old—That the child is smart & active and now resides with its parents." (Waggoner, 61a)