By the end of Lois Lowry's novel, Annemarie has not seen Ellen again. Annemarie knows that she and her family did everything possible earlier in the war to protect Ellen, including having her masquerade as Annemarie's sister. However, Annemarie has not yet had the joy of being reunited with her friend. It is important to bear in mind that the war has only just ended at the point when the novel ends. If Ellen and her family were to be able to come home, it is likely to take some time for them to make their way back.
Annemarie very much hopes that she will be reunited with her dear friend one day. In fact, she hopes to be able to return Ellen's Star of David necklace, which has been stored with Lise's wedding dress for safekeeping. In a quiet act of faith that she will see her friend again, she asks her father to repair the necklace's clasp so that it will be ready for Annemarie to wear upon her return.
Since Annemarie has no way of know knowing what has happened to Ellen and her family, she can have no certain knowledge of whether she will see her friend again. It seems likely, however, that the family survived the war. Thanks to Sweden's neutrality and acceptance of Danish Jewish refugees, it is arguably the safest place for the Rosen family to have been during these troubled years.