Interesting markings. The three crowns mark in an oval shield is the Swedish import mark introduced 1.1.1913,
yes 1913! The Swedish three crowns mark or also called "cat's paw" was introduced 1754 and it looks like this:

Please compare the shield with the shield on your spoon that has an oval shape.
Undoubtedly Lucas van der Hagen marked LVH 1722-
1765 in Stockholm but with serif letters. However, I cannot see any serifs here and not either the first letter. In addition, the year mark and Stockholm's town mark are missing too. If Hagen had remarked it later, [b]why would he have done that?
I don't think the letter B is a maker's mark, but not either a year mark because of its shield. At that time the year marks were punched without shields. The "B" could be the Swedish importer's mark/logo after 1912 because it is beside the import mark, but...?
I doubt very much that your spoon is of Swedish origin. The late import mark (1913) speaks for that. Unfortunately I cannot tell neither the maker nor the country of origin. Let's hope somebody else knows that.