One challenge that you will have with four players against the Hobbit quests, is the riddles in the 3rd Quest. You pretty much need to be playing one or at most two sphere decks to have a chance of answering the riddles correctly in the 3rd quest. There are currently only 9 Dwarf heroes, which makes this tricky, but I guess you could do something like this:
Gimli + Beorn + Gloin: Tactics with splash of Leadership for cards like Campfire Tales and Second Breakfast which are great in 4 player games. Get a Song of Battle on Gloin to help pay for Citadel Plate on Gimli.
Dain + Dwalin + Nori: Spirit with Dain for quest buffing. This will include your cancels and threat lowering as well as Cram to make sure that Dain stays ready. Be sure to play Spirit Bofur to combo with Nori's ability.
Thorin + Bifur + Ori: Lore with a splash of Leadership. This deck will use Erebor Recordkeeper, Erebor Hammersmith, Miner of the Iron Hills as well as some healing. It's not thematic but with all of the card draw Protector of Lorien becomes amazingly powerful. This is where not having Dwarrowdelf hurts you because Legacy of During and Daeron's Runes are both excellent cards in this deck, the former of which is near-essential to an all dwarf strategy.
Thalin + Legolas + Bard: This deck is very focused. Quest every turn with Thalin and then use Bard/Legolas and cards like Swift Strike and Hands Upon the Bow to finish off the enemies that Thalin has weakened by questing. This will include Feint so to give breathing room before your ranged characters kill everything that moves on the counterattack.
Not perfect, but it's not easy to make this work for 4 players without Dwarrowdelf cards in your card pool.