This looks like the Marriage of daughter Elsie born approx 1887. so would assume her parents married some time around the 1880s

California, County Marriages
Name: Reginald Meaker
Event Type: Marriage
Event Date: 22 Sep 1914
Event Place: San Francisco, California, United States
Gender: Male
Age: 27
Birth Year (Estimated): 1887
Father's Name: Henry A Meaker
Mother's Name: Elizabeth Dinham
Spouse's Name: Elsie Heward
Spouse's Age: 20
Spouse's Gender: Female
Spouse's Birth Year (Estimated): 1894
Spouse's Father's Name: John Henry Heward
Spouse's Mother's Name: Theresie Nordquist
Page: 377
GS Film number: 1405838 , Digital Folder Number: 004640218 , Image Number: 00492

1910 USA Census
John H Heward
AGE IN 1910: 48
BIRTH YEAR: abt 1862
BIRTHPLACE: England
HOME IN 1910: Reno Ward 5, Washoe, Nevada
RACE: White
GENDER: Male
IMMIGRATION YEAR: 1882 arrive in USA nationalised 1887
RELATION TO HEAD OF HOUSE: Head
MARITAL STATUS: Married
SPOUSE'S NAME: Thersia Heward
FATHER'S BIRTHPLACE: England
MOTHER'S BIRTHPLACE: England

John H Heward 48 England
Thersia Heward 37 Born in Sweden as were her parents arrived 1889 nat. 1891
Harland L Heward 17 b Idaho
Elmer S Heward 16 b Idaho
Elsie R Heward 15 b Montana
Ellen T Heward 12 b Montana
Frances L Heward 11 b California
John H Heward 9 b Montana
......................................................................................

USA 1920 Census
John H Heward
AGE: 58
BIRTH YEAR: abt 1862
BIRTHPLACE: England
HOME IN 1920: Gerlach, Washoe, Nevada
HOUSE NUMBER: Farm
RACE: White
GENDER: Male
IMMIGRATION YEAR: 1882
RELATION TO HEAD OF HOUSE: Head
MARITAL STATUS: Married
SPOUSE'S NAME: Theresia Steward
FATHER'S BIRTHPLACE: England
MOTHER'S BIRTHPLACE: England
NATIVE TONGUE: English
ABLE TO SPEAK ENGLISH: Yes
OCCUPATION: Farmer
INDUSTRY: Stock Farm
EMPLOYMENT FIELD: Employer
HOME OWNED OR RENTED: Own
HOME FREE OR MORTGAGED: Free
NATURALIZATION STATUS: Naturalized
ABLE TO READ: Yes
ABLE TO WRITE: Yes

John H Steward 58
Theresia Steward 47
John H Steward 19
Frances Steward 21
Helen Blair 22 Married daughter
Gladys Blair 2 G/daughter

Found this which might be worth looking into

John Henry HEWARD
birth: 23 September 1867 Forest, Durham, England
death: 7 May 1920 Reno, Washoe, NV

marriage: 1890
Helena, Lewis & Clark, MT


Kristina Teresia NORDQUIST
birth: 28 July 1872 Norra, Gunnerudstorp, Ostra Emtervik, Sweden
death: 8 January 1939 Reno, Washoe, NV

marriage: 1890
Helena, Lewis & Clark, MT

Parents:

Jons Elovsson NORDQUIST
birth: 1830 Sweden
death: 8 December 1878

Britta MAGNUSDOTTER
birth: 20 November 1833 Smedserud, Ullerud, Sweden
death: 2 January 1903 Sweden

England & Wales, FreeBMD Birth Index
John Henry Heward
REGISTRATION YEAR: 1861
REGISTRATION QUARTER: Oct-Nov-Dec
REGISTRATION DISTRICT: Teesdale
INFERRED COUNTY: Durham
VOLUME: 10a
PAGE: 193


England, Select Births and Christenings, 1538-1975
NAME: John Henry Heward
GENDER: Male
BIRTH PLACE: Middleton in Teesdale
BAPTISM DATE: 29 Sep 1862
BAPTISM PLACE: Middleton in Teesdale, Durham, England
MOTHER: Nanny Heward
FHL FILM NUMBER: 1894229

from 1920 census

Helen Blair 22 Married daughter (On the actual census where it states married / single etc
it just as a cross )

Gladys Blair 2 G/daughter (daughter of Helen it states b Nevada, father b Pennsylvania, mother born Montana.

Not sure if she is still married, a widow, separated or divorced.

I have not managed to find her in the 1930 census.