Can someone tell me, if Yvonne's last name is either De Carlo, or DeCarlo. I couldn't tell from this screen shot.

It's "De Carlo" with the space.

Thanx! That's what I thought it was. :D

The Munsters' Revenge credits her as DeCARLO (as all the credits are in caps), but I think that's an error. The surest source is her autobiography, which says De Carlo.