Saw a tweet that said that the reason Claudia couldn't find Madeleine is because Madeleine already overcame any past guilt/regret clinging to her. She passed on while Claudia is in purgatory. Claudia's rage and spite towards Louis and Lestat continues even after her death, even with calling her life "bleak." Perhaps this seance finally let her pass on, letting out her anger as the last nail in the coffin to fully detach herself from Louis and Lestat and reuniting with Madeleine in the beyond.
I'm taking that as canon, I can't live with the idea of Claudia being stuck in darkness forever

















