It seems very unlikely to me that "AB" would here denote "Alberta," simply because the region was only acquired by the Dominion of Canada in 1870 and remained largely unsettled until after the 1885 North West Rebellion was put down. The name "Alberta" was merely one district of the Northwest Territories until the Province of Alberta was established in 1905. The marks on the spoon would seem to predate the establishment of Alberta.
I wonder if the "AB" here is not the "AR" of Adam Ross. Trev has posted several variations of Adam Ross' touchmarks in the Contributors' Notes. See:
viewtopic.php?f=38&t=31885Among the many marks Adam Ross used, I see at least a strikingly similar AR and the rather distinctive lion passant, although not used in the same combination as on this spoon. That said, I cannot account for the conjoined LR or RL mark. This is pure fancy on my part, but I wonder if it might be the mark of either a retailer or a successor to his business, perhaps a descendant of first name beginning with L.
None of what I have written is conclusive, of course, but hopefully these musings will point someone else toward a definite attribution.
Regards
David R