Dear wolf is a paper note in the Fallout 76 update Wild Appalachia.
Location
The note can be found in Van Lowe Taxidermy, on a table in Calvin's bedroom on the third floor. It is obtainable during Lying Lowe.
Transcript
My friend WOLF,
I imagine you're here to follow my trail.
I've left what you'll need in a display case downstairs.
Good luck.
-Blacksheep
What the hell is this?
-Shelley