Ellen Connolly born 1845 in Clifden

My 3rd great grandmother, Ellen Connolly, was born on 23 Dec 1845 in Clifden, County Galway. The birthdate has been determined by the 1880 U.S. Census, and her headstone. However, the 1900 U.S. census lists 1850 as the birth year and 1870 U.S. census lists 1847 as the birth year). According to the 1900 U.S. census, Ellen arrived in the U.S. from Ireland in 1865, and married Joseph Dunbar in 1867. They had 5 kids: George, Kathryn F., Elizabeth, Joseph William, and Richard (I have lots of records on the kids). I cannot locate Ellen’s immigration or marriage records in the U.S. or any records of her birth, baptism etc. in Ireland. She died 6 Nov 1905 in Monterey, California, USA. 

According to her sister Catherine Connolly's (1825-1901) obituary, siblings Ellen, Catherine, and a brother Joseph Connolly were born in Clifden. I cannot locate Ellen’s siblings’ birth, baptism, or immigration records either. Catherine Connolly died in Oakland, California, USA on 30 Aug 1901. Catherine's obituary mentions being an aunt to Ellen's children, as well as an aunt to a Bridget Lydon Connolly (born 30 Nov 1851 in County Galway). I presume that Bridget is Catherine & Ellen's brother Joseph Connolly's daughter, but I cannot verify this.  Most of the family (Catherine, Ellen’s husband, and Bridget and her husband) were in the laundry business in San Francisco and Healdsburg, California.

Thank you in advance for any help in finding records for Clifden native siblings Ellen, Catherine, and Joseph Connolly. I was not able to find any clear matches on rootsireland.ie, FindMyPast, or Ancestry, etc.