I feel like the easiest solution would just be to say that Tav no longer has a home as we've been assumed dead. Heck, the home could be destroyed. The Nautiloid wasn't exactly gentle when abducting people.
Though I will say I don't see a problem with a former urchin having an upper class home. Urchin implies you were on the streets during your childhood. Assuming you're only 20 years old that could leave you with a few years to amass a small fortune, which isn't that hard for someone skilled enough to take a level in a class. Amassing wealth might take a long time in Medieval Europe but in Faerun it can happen very, very quickly. It's just also very, very dangerous.
