I thought I might try to help you on this query, but I might need some additional clues. Do you know if/when/whom she married? Do you know when and where she died?
I find two individuals named Grace Lalonde, one in Ontario and one in Quebec in 1911, as well as an agnes Lalonde in Quebec, all of about the right age.
Did she go by the name Agnes or Grace?

Perhaps some additional information would be helpful