SPOILERSFrenzy (Dreamhouse Kings, Book 6)
by Robert Liparulo
They go through a portal and find their mother. And then David meets Jesus.
Jesus. Who then heals the entire family through David, conveniently avoiding all those pesky child abuse rumors the family was suspected of in the first book (thanks to the beatings they were receiving from things like cannibals, the roman army, Nazis, Civil War soldiers, Atlantians, etc).
I'm so glad this is over. I will make like The Vampire Diaries and end my misery even if there will eventually be a continuation of the series.