Nicholas and Isabel Den
Isabel was born in 1855, the daughter of Jose Ramon and Isabel (Alviso) Arguello. She married Nicholas Den (born in 1848) at Mission Santa Barbara about 1878. Ramon was the son of Dr. Nicholas Den of Ireland. Along with Dr. H.H. Warburton, he was one of only three doctors practicing in Alta, California.
Source: Legendary Locals of Santa Clara (you can find a copy at City Lights)