What happened to Wizet again?

They merged, Nexon = parent company.

Wizet=Maker of MapleStory.
Nexon=Promoted+made it better in a way. More support.

That's not what a "merge" is, but yeah pretty much.

I would say Wizet was absorbed into Nexon.

the most notable change was the moving of the servers from new york city to California.

That happened relatively late in the game. The people now referred to as "Nexon America" were pulling the strings back as "NxGames", and even before then. There wasn't ever a real point of it being Wizet one moment and Nexon the next. People erroniously draw a line, however... I think the most commonly drawn line is the point where NxGames changed their name to Nexon America. I think THAT is the point most people see as the cutoff, but really, they're just wrong. There was never a binary switch like that.