The 1910 census is my Mary. Before she got into police work she designed lamp shades and I believe worked for Tiffany's for a short period. I also saw the 1900 census recently and it is definitely a good guess to her and William. I wish Mary's son was with them on the census to help confirm that record.
I am going to look into the death record of William A Hamilton that you provided. Mary's son changed his name from John Crowley to John Anthony Hamilton and I am wondering if this William has a middle name Anthony.
I appreciate your help so much and hopefully it will all lead to the origins of my surname.