Mattie in Moorcroft or Modesto?

I've admitted defeat - I cannot find what happened to Mattie FAIRCHILD, dtr of John and Lucinda (BOYCE) FAIRCHILD.
Known info: mentioned as the surviving daughter of Lucinda when she died in 1908, as Mrs J E SULLIVAN of Moorcroft, Wyoming. Mentioned by Grandma VIELE (so pre 1956), as last heard of in Modesto, California, as a nurse.
May have been called Winifred.
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