Franklin's memorial is in the cemetery, as you might have guessed.

The large statue at the top of the first stairs is a memorial to Franklin Thornton and other Thorntons who died away from home. That's the one you want.

The information you want from it is the last date on it, which is the date the statue was dedicated. Look at the plaque after you read Charlotte's journal, and Nancy will say something about this being the date Charlotte mentioned.

As it said in the journal, you'll need these numbers to solve some puzzle in the shape of the drawing -- a rectangle with ten smaller squares around the edges. Have you seen something like that?

How about the locked door in the cellar?

Tunnel with Locked Door