The 14JUL1870 issue of the, "Saint Croix Courier", of Saint Stephen, Charlotte Co., NB had the marriage, abstracted as:
"m. At residence of bride's father, Little Ridge (Charlotte Co.) 13th inst., by Rev. John Turnbull, Margaret Isabella McKENZIE eldest d/o John McKENZIE / John Smith, Humboldt County, California."
This indicates that John had gone to California, and returned for Margaret. Another marriage (Saint John, "Morning Telegraph", 11JAN1868) is:
"m. Tuesday morn. 7th inst., by Rev. N. McKay, John Smith, Petersville (Queens Co.) / Miss Margaret Jane ROBB, same place."
The former marriage seems more likely the one you seek. The, "St. Croix Courier", (29OCT1891) reported:
"Our Moore's Mills correspondent writes: News has been received of the death of John Smith of Marysville, Butte County, California. He was the eldest son of Stillman Smith of this place; this being the third son who have died in California."
It seems shortly after this that Stillman Smith, and his daughter, Mrs. Della Berry (who lived there) made there way to Eureka, CA. (About OCT1892.)
In St. David Parish, Charlotte Co., NB, in the 1851 census, Stillman's family is given as:
Smith Stillman M Head 33 Birth Farmer (Prop.) Smith Margaret F Wife 25 Birth Smith John N M Son 7 Birth Smith Thankful F Daughter 5 Birth Smith Sarah F Daughter 4 Birth Smith George A M Son 2 Birth Smith Edwin M Son 2 mos Birth