It can be addressed from "The guys & gals from PCSpecialist forum". I believe the nephew did inform the widow of the effect he had on the forum. Anyway, I'd be happy to chip in for a card or anything else that others decide.
A card from a community that respected, valued and cared for the guy would be entirely appropriate and probably quite warming for the family. Make sure to express such sentiments in the card. I'm afraid I didn't know Vanthus, but it sounds like he was very valued here.
