I didn't find her death info either and I looked in Ancestry and FamilySearch.
You can do a Google search for Louisa County Iowa Cemeteries and look for her in the inventoried cemeteries.
If you don't find her, you can contact the Louisa County Historical Society's Genealogy Committee, www.rootsweb.ancestry.com/~ialcgs/
and inquire if they have additional info about her. Successful Searching!