Do you keep valuables in epilogue rdr2?
You get to keep everything except your horse and money, but you won't have access to your full array of stuff straight away in the epilogue. If your horse is the white Arabian stallion from up north, which IIRC is the best horse, that respawns anyway. Make a manual save just to be sure.
Can John get the money from Beaver Hollow?
If the player decides to go back for the money: After saying his farewells to John and giving him all of his possessions, Arthur returns to Beaver Hollow, in order to take the gang's money stash hidden in the caves.