Just for some added information, it was a talented family. Charles MacArthur (her husband and James' father) was a writer and partner of Ben Hecht, most famously on the plays The Front Page and The Twentieth Century (later adapted as the musical, On the Twentieth Century). As a screenwriter, Charles MacArthur got two Oscar nominations, for Wuthering Heights (with Hecht) and Rasputin and the Empress. Other films they wrote include Barbary Coast and the film story for Gunga Din -- as well as the aforementioned The Sin of Madelon Claudet, which won Helen Hayes her Oscar.
Which brings us back to Helen Hayes --
And just for fun, here's a bonus video -- a 3-minute sequence from Hawaii Five-0 with Helen Hayes and her son, James MacArthur.