I found a short newspaper article mentioning Capitola:
The Oregonian newspaper Oregon October 16, 1892 page 6
Salem, Oregon Oct. 15 Capitola Damme from Grant's Pass, was committed to the insane asylum today.
The Oregon State Archives http://genealogy.state.or.us/http://genealogy.state.or.us/ also mentions another commitment for Capitola: Case# 102 Name Damme, C. Date Dec 12, 1893 Record Type Commitment County Josephine Source Hawthorne Asylum Identifier Housewife Remarks F
I found a mention of her death: The Oregonian Date: August 24, 1899 Location: Oregon page 5
DEATHS Capitola Damme, 48 Clark Street, tuberculosis.
She is buried in the Lone Fir Cemetery that is managed by Metro Parks. If you contact them, they are very good at sharing what is in their records. Metro cemetery services 503-797-1709 | 503-797-1849 fax email@example.com
Last name Damme First name Capitolia Death or burial date* 8/23/1889 Grave number 2N Lot 101 Section 35 Lone Fir Pioneer Cemetery Southeast 21st Avenue and Morrison Street Portland, Oregon
William is also buried there: Last name Damme First name William Death or burial date* 2/8/1903 Grave number 1N Lot 101 Section 35
I found a death notice for William: The Oregonian February 8, 1903 page 12 DAMME-Died at St. Vincent's Hospital, February 6, 1903, William Damme, aged 48 years, late residence 74 Randolph street, Albina.
I hope this information helps you. Hopefully Metro Parks will have something for you in the information they are given for burial.