Yes, you can give more than one loot to other players in return for assistance with a battle. You can give multiple loot to the same person or you can give one or more loot to each of several different players.Originally Posted by ElderGias
The only limitation is that in PvP battles, an assisting player can only help one of the two players in the battle. You can't assist both sides.
Assistance is only good for a single battle (ie. a single die roll). If you decide to attack the next monster in the stack you have to offer new loot in order to gain assistance.