I believe there was a 5th evening at Town Hall with Rosalind Russell on September 23, 1974, Joan Crawford's last public appearance at the reception afterwards. See footage in link.
It's disturbing that the writer of the book says Davis was on Broadway in the 80s. That's so easily checked.
I saw a toddling Davis say the line at what is now David Geffen Hall (not Broadway) on one night at Lincoln Center in 1989.