Edith is 24. The flashback at the beginning with Eleanor's ghost happens when she's 10, and then the main action takes place "14 years later" according to a title card onscreen
Thomas is 34, based on the date of the newspaper announcing Beatrice's murder (1879), his age at the time (12), and the present year shown in Carter Cushing's checkbook (1901)
Lucille is 36, from the same logic above. (people seem to enjoy interpreting their age gap as much larger, which is weird to me because it's stated onscreen? by Alan when he's confronting them near the end? even if you don't pause the movie to read document dates- understandable -"12 and 14 when Beatrice was murdered" makes the gap clear)