On the 1900 census for Worcester Mass, there is a listing for Hattie M.L. Childs, musician.  It's got to be her!  She lived at 11 Murray Ave (possibly in an apartment) with her husband Harry A. who was a bookkeeper in a Printing? shop. She was born in Apr 1870, as was her husband.  They had been married 5 years and had no children.

Searching marriage records by Harry's name, I found a listing for him and Hattie M Lynn Kittridge on 12 April 1895,  so I really do think it's her. However on the marriage record, she's listed as a bookkeeper, too.  I wonder if she just up and decided to play the harp one day...

Her parents on the 1900 census are listed as: Charles W Barker,​ Sarah E Barker, on her marriage license they are: Charles W, Sarah E Knapping. ???

And sadly, Harry is listed as divorced in the 1910 census and living back at home with his mom.