RIP Luke the Hammy

We had such a great night tonight at a Halloween event but came home to find that Luke the hamster had died. I told Jack while he was in the bath and his little face crumpled up and he cried and cried, it was awful. To see him so upset and so grieved is really hard. He also said that having Luke in his room gave him comfort, that he liked having somebody else share his room at night when he got scared. I feel so bad for the little guy.
Now what to do to make him feel okay about being in his room without his hamster buddy? Getting another one is not an option.