The official The Host Movie facebook page just featured this video.
The artist is from Australia. Her name is Czarina. According to her official website:
My Soul is the first single release from her new album with the same name. Written by Czarina, produced at Tender Trap Studios (Northcote, Melbourne) featuring Anita Quayle on cello, this beautiful ballad was inspired by Czarina’s favourite novel, The Host, by Stephenie Meyer. To celebrate the completion of the album and official video clip, there will be a launch party on Sunday March 25, 7.30pm at The Chandelier Room, Moorabbin, Melbourne where Czarina will showcase a set of original songs she has penned from all her albums. Her new album My Soul, is especially suited for background lounge music and has soundtrack potential.