Translation:Hoş geldiniz, hanımefendi!
Hanım is usually used as an honorific; like Selcen Hanım from a previous question. I'm not 100% sure, but using it as a noun for someone you don't know is rude. Hence the polite "hanımefendi"
Both forms are abundant actually. I'll make sure both spellings are accepted on Duolingo.
the correct spelling is with a space according to TDK; we accept it without the space, with a typo message of course