At 4th level, a ranger forms a bond with his hunting companions. This bond can take one of two forms. Once the form is chosen, it cannot be changed. The first is a bond to his companions. This bond allows him to spend a move action to grant half his favored enemy bonus against a single target of the appropriate type to all allies within 30 feet who can see or hear him. This bonus lasts for a number of rounds equal to the ranger’s Wisdom modifier (minimum 1). This bonus does not stack with any favored enemy bonuses possessed by his allies; they use whichever bonus is higher.
I've got a player with this ability and the party is fighting a group of demon's (on of the ranger's favored enemies, Evil Outsiders). The player wants to use the Hunter's Bond to give her companions a +2 advantage when fighting one of the demons as her move action, and then use a second move action to give the bonus toward another demon. So all the players would get a +2 favored enemy bonus against two demons. There are four demons total, so that would mean after another turn, everybody gets to treat all the demons as favored enemies (at +2).
Does this violate the rule that grants the bonus to a single target? It is not clear whether the words "single target" limits the ability to only one enemy at a time or just one enemy per move action.
I'm inclined to think it limits the benefit toward just one target, with the next sentence spelling out other requirements, such as the time it is in effect and how long it takes to activate.