Elizabeth Vance had 7 illegitimate children:
Mary VANCE b. 1831
Nancy A. VANCE b. 1813 "Devil Anse's Mother"
James "Bad Jim" VANCE b. 1832
Richard VANCE b. 1822
Zeb VANCE b.
Phoebe VANCE b. 1812
Sarah VANCE b. 1815
So to answer your question Anse's Mother was Jims's sister.
Here is some good info on the subject.http://timothyv.tripod.com/index-16.html