The 1900 census shows that Andrew Dyson Married Delia 1882. I would put the time frame for Nancy's death after 1905. There was a dispute over his Naval Pension about 1905.I have copies of affidavits from her good friend Mary Wright from NC and her brother Albert as witness to Andrew's and Nancy's marriage. I do have a copy of that Marriage record but cannot locate one for the marriage of Andrew and Delia.
The only census that I have located for Nancy so far is the July 12 1870 Census Beaufort Carteret NC where she is listed as Nancy Dison. I have been unsuccessful in finding any other census on her. I have located Albert Wigfall on three Census: July 12 1870 Carteret NC. It lists his parents as Owen and Jane Wigfall. I believe this may be him because Nancy's mother's name was Jane Wigfall. He is also listed on the June 16 1870 Census in New Berne Ward NC where he is listed as an apprentice Harness Maker. I have him on the 1920 Census where he resided in Brooklyn with his wife Nellie and 5 children. Nellie is also listed in the 1910 Carteret NC Census as Divorced and the 1920 Carteret NC Census as Widow, so I am assuming he died between 1910 and 1920 but I can not find any subsequent info on him.