This is for eliminating the Death (and obituary?) you found. The following appears to show that the Ann McDONALD ms O BRIEN who died 1912 (per the death cert), is not the mother of your John b 1877. That Ann's son John was born abt 1856 and she was already in her mid 40's in 1870. The address 642 Maple Street ties the following:
Found: Bernard J McDONALD b abt 1855/56 MA,
1900: 786, Locust Street, Fall River a widower, with his elderly, widowed mother Ann age 70 (imm 1850, 12 children born, 7 still living) & siblings, one of which is Patrick E, McDONALD age 41, single and born Jan 1858,
1910: Bernard is still with his widowed mother, and some siblings (but not his brother Patrick). Both Census state his father b Ireland. He married in Fall River in 1887 at age 32 to Annie BARRY age 20. The marriage recorded he was a Clerk, b Fall River, parents Patrick & Ann. She was a Domestic, b Ireland, parents Patrick D. & Eliza. It was the first marriage for the both of them. The 1910 Census says Bernard's mother Ann arrived in US 1845 and their address is: 642 Maple Street.
In 1870, Bernard is 15 and in Fall River with his family:
Patrick McDONALD 45, Wool Sorter, b Ireland
Ann McDONALD 45, Keeping House, b Ireland
Thomas McDONALD 17, Works in Wool Mill
Bernard McDONALD 15, Attending School
John McDONALD 14, Attending School (b abt 1856)
Patrick McDONALD 12, Attending School (b abt 1858)
Mary A McDONALD 11, Attending School
Hugh McDONALD 8, Attending School
Catherine McDONALD 7, Attending School
All children b MA.
1910 DEATH: Patrick E McDONALD Single age 52 (born abt 1858)
Died 5 April 1910
Residence: 642 Maple Street, Fall River
Occ: Barber
Parents: Patrick McDONALD & Ann O'BRIEN
Informant: Mother.
1912 DEATH: Ann McDONALD, age 81, b Jan 1831 Ireland
Died 12 Apr 1912
Maiden Name Ann O'BRIEN
Husband: Patrick McDONALD
Residence: 642 Maple Street, Fall River
Occ: Retired
Father: Patrick O' BRIEN and Mother: Catherine (ms) SHERIDAN
Informant: Mary A McDONALD
Cheers
AMBLY