Hi.....i have found the following for the person you are looking for in the 1911 census in No. 20 St. Alphonsus Street, Waterford:
Mary Anne McDonald..married....age 48
G Sarah Noble McDonald...daughter...single...age 20
Mary Anne Mcdonald...daughter...single...age 17
James McDonald...son....age 11
David McDonald...son...age 9
It states that Mary Anne is married...not a widow...indicating that her husband was still alive, although not at home on Census Night.
It also states that the marriage has lasted 25 years and that 7 childeren had been born but only 4 were alive at that time.
Hope this might help you.
Regards,
Tom.