We all know that Lena was captured and aged in her cell right. However I do have a question. Did she age to death though? Even if not is it plausible that her daughter will return for revenge once she finds out what happened to her mum?
I doubt that Lena is dead. It is possible for her to complete the ritual in prison though using the prison guards. The other Spinnetod, Charlotte I think, was alive for some time for refusing to commit the ritual needed for their youthful appearance. Sally on the other hand we don't know what her reaction might be. She will have to kill to maintain her youthful appearance however.