I have found an Erik Christiansen arriving in the USA on 23 Sep 1929 on the S.S. United States from Copenhagen. According to the manifest he is 20 years old and born in Copenhagen. He lists his nearest relative as his mother Olga Christiansen of 11 Kg. Georgavej, Copenhagen.

I found Olga Anna? Karla Christiansen in the 1930 Danish census for Kong Georgsvej 11, København. She was born in København on 31 Jan 1889 and is divorced.

Is this your Erik?

Sincerely,
Paul
North Carolina, USA