The tax lists from 2009 show that Margareth Aslaug Heier was alive and living in Oslo. She is the only Margareth Heier listed in all of Norway. Her birth year is shown as 1916.http://skatt.adressa.no/nyhist/2009/person?id=855760
I don't believe there are tax lists after 2009. She is not listed in the present online telephone book.