Good Answer

That was just how the developer of the mod named it, most of the mods with smaller titles start with vB but mods with longer titles such as Threadmins and Group Moderators would not look right if it was vBThreadmins and Group Moderators.

Branding vB standing for vBulletin which the developer is indicating the Mod is for vB (vBulletin)
Also the URL index vb_donate.php

It might have been DBTDonate or dbt_donate.php

I prefer not to have vb_donate.php or dbt_donate.php in the URL index when Branding Free is purchased.
It's so early 2000's as in so last year.

dragonbytetech Threadmins and Group Moderators. php would be way to long.

Solution

Voted 'Best Answer'

Generally if a mod is a single word or two words it will have the vB prefix (except where that prefix is already in use by another mod). For longer mods we drop it.