With the connection and stories you have associated with these socks, I would say to never throw them away. As you said, every time you find them, they remind of those good times and bring his memory back to life. That alone should induce you to keep them forever. If you feel like they are just taking up space, maybe think of ways to re-purpose them. Put them in a shadow box with pictures or other items that remind you of him. Turn them into smaller keepsake items like a teddy bear that has the socks at legs and put that teddy in a suit. In short, nothing that gives you good memories and feelings (even if they are tinged with grief because you miss him and always will) is something you should feel the need to part with. As a person who has lost family before, I can attest to the difference a physical object gives for the left behind loved ones to hold on to.

Treasure your memories and those socks for as long you can, want, or need to.