Hi, I found two sons of William and Mary's. Robert D. was born abt. 1868 in MO and died 22 Feb 1949 in Spokane (doesn't say city or county) per death cert #3573. WA Death Index 1940-1996.
Levi S. Hurlbert was born abt. 1881 in WA and died 17 Sept. 1952 but doesn't say where per death cert #16668. WA Death Index 1940-1996. I'm guessing he died in Spokane too since he lived there in 1930.
You can request a copy of any obituary in WA state from email@example.com. Send them the name, where and when died and if they find the obit in the newspaper microfilm, they will email it to you for free. Descendants should be listed in the obit. Also an inexpensive way to verify if these two are your Hurlberts. Good Luck!