Words like dig and mig (migselv) was not supposed to be used after 1938 when it became correct to use deg and meg (megselv). (Deg means you and meg means me). But of course people didn't change their usual way of writing at once. I remember getting letters in the 1970's from an old woman still using mig and dig.
Other oldfashioned words are efter today we use etter (after), hendes today hennes (her), billedet today bildet (the photo/Picture). My guess is that this was written in the 1930's or 1940's.
Does the names Henning, Sofie and Krestine sound familiar? (The fourth name looks lik Krestian, but I'm not quite sure I read it correct.)