familysearch.org shows MA births: Helena Alice Elertsen b. 06 Apr 1885 Cambridge, parents Emil C. and Annie.Says her father is from Norway and her mother from Ireland.
Also the marriage of Caroline to James Maher is indexed under "Caroline Evelyn Ellertson".
I think the marriage of Caroline's parents may be: Emil Eilertson to Mary A. Beattie - married 20 August 1883, Cambridge. He was 27, a painter, from Norway. His parents are given as Andrew and Lena. She was 26, from Ireland, her parents are given as William and Barbara.
In 1900 Emil C Eilertson is a widower living with parents Andrew and Lena in Boston. b. Dec 1855 and emigrated 1872.In the same census, Caroline E Eilertson is listed (with two other Eilertson children) as "niece" in the house of William Rogers and wife Margaret (probably nee Beatty, brother in law WIlliam Beatty is also in the household).
Mary Ann Elertson d. 26 Jan 1896 aged 39 (wife of Emil C, daughter of William and Barbara Beattie).
There is also marriage/death for siblings of Emil: Anna L. Eilertson (b. 1864, m. 1886 to Walter S. Hall, d. listed as Anna Eilerston in 1895) Thelda T. Eilertsen (b. 1869, m. 1894 to Tellef J. Hamre Olof S. Eilertson (b. 1861, m. 1894 Elise C. Tonneson)
Mother Lena (b. Feb 1833) d. 22 Jan 1907 in Boston and her parents are given as Ole Olsen and Severine.