Attack Action: An attack action is a type of standard action. Some combat options can modify only this specific sort of action. When taking an attack action, you can apply all appropriate options that modify an attack action. Thus, you can apply both Greater Weapon of the Chosen and Vital Strike to the same attack, as both modify your attack action. You can apply these to any combat option that takes the place of a melee attack made using an attack action (such as the trip combat maneuver), though options that increase damage don’t cause attacks to deal damage if they wouldn’t otherwise do so (such as Vital Strike and trip). You can’t combine options that modify attack actions with standard actions that aren’t attack actions, such as Cleave.
Extra Action: You can spend a hero point on your turn to gain an additional standard or move action this turn.
Vital Strike (Combat)
Benefit: When you use the attack action, you can make one attack at your highest base attack bonus that deals additional damage. Roll the weapon’s damage dice for the attack twice and add the results together before adding bonuses from Strength, weapon abilities (such as flaming), precision-based damage, and other damage bonuses. These extra weapon damage dice are not multiplied on a critical hit, but are added to the total.
Here is the question: Can i make a full-attack and then use a hero point extra action and make a Vital Strike??
Sure. Hero points are spiffy.
Ok, so let's level up the question, because this is the "wrath of the righteous" adeventure path!
Amazing Initiative (Ex): At 2nd tier, you gain a bonus on initiative checks equal to your mythic tier. In addition, as a free action on your turn, you can expend one use of mythic power to take an additional standard action during that turn. This additional standard action can't be used to cast a spell. You can't gain an extra action in this way more than once per round.
If i have Mythic Tier 2, with Amazing Initiative and use it and the hero point would it be 2 vital strikes on top of my full-attack???
Neither the hero point nor the mythic ability put a cap on how many standard actions you can have total. So yes, for a cost of one hero point (a high cost!) plus one use of mythic power (not so much but still significant) you can get your normal slew of actions plus two standard, which you can use to do a total of one full attack plus two Vital Strikes if you like. And you still have a swift action left over! :-)