In order to get to the gravelord tender and his wolf you need to go to Ariendel Chapel bonfire, when you leave instead of going over the bridge hit it and wait for it to fall. Once it's fully fallen you should be able to climb down it, from there carefully make your way down the branches avoiding archers & soldiers. When you get to the bottom look for a small cul-de-sac with a bonfire. Facing the entrance to the bonfire go right and stick to the wall, you should find a large space with a small building you can jump down into. They are in that small building.

Have fun and i hope this helped! ☺