In a multiplayer game, you consider each opponent. If you have fewer lands than one opponent and less life than another, for example, you'll get both of those bonuses.

No player may take any actions while Beza's ability is resolving. For example, you can't use the Treasure token to try and change the outcome of any of the other comparisons. However, in some unusual cases, that Treasure token might enter as a creature, in which case it might impact whether you get Fish or not.

You compare the number of lands you control with the number of lands each opponent controls as Beza's ability resolves. At that time, if at least one opponent controls more lands than you, you'll create a Treasure token. Similarly, you compare life totals, creatures controlled, and cards in hand with each opponent as Beza's ability resolves. If at least one opponent has more life, creatures, or cards in hand than you, you'll get the appropriate bonus. It doesn't matter if you qualified for any of the previous bonuses or not.