There are a couple of ways:
1) If the users only need to view static maps, have your VB app save the appropriate views as web pages at regular intervals.
2) If they need interactive maps, you can get a multi-user license for each simultaneous user (ActiveX or the full MapPoint app). I think ActiveX will work over the web for the low numbers you are talking about, but I think you still need more licenses. Ask MapPoint sales.
3) If your records are just points (not shaded areas, etc.) you could consider developing on MapPoint .NET instead... but you probably don't have the kind of volume to make that cost-effective.