I'm no expert on Wisconsin Genealogy, but I have some general thoughts that may fit this situation, that have worked for me. It's thought she died 7/9/1888 in Dell Prairie, Adams, Wisconsin, right? Although death records of that time are less than complete and sketchy, a death record for her does exits within the searchable indexes. If you have access, travel to the town and perhaps a friendly town clerk can locate the original ledger. It is absolutely quite possible it will reveal her parents. These indexed don't contain all the information available.
Also, here is a lesson I learned, if the record doesn't show up, check the neighboring towns. People don't always die at home, there are a thousand reasons why someone may be traveling to the next town over. Towns and Villages within Towns will have totally separate records. If you can't travel, you can try the telephone, it may work, it may not. It's not impossible. Somtimes you can get what you need over the phone and then have a copy mailed to you. Your odds will greatly increase with a person a visit.