What is the correct net ionic equation for the neutralization of phosphoric acid?
Phosphoric acid dissociates into hydrogen ions and $\ce{H2PO4^-}$ ions in water.  This then can dissociate further, but $\ce{H^+}$ and $\ce{H2PO4^-}$ are the primary ionic species you'd find in a phosphoric acid solution.  

$\ce{NaOH}$ dissociates completely into $\ce{Na^+}$ and $\ce{OH^-}$ ions.

The reaction would then be between $\ce{H^+}$ and $\ce{OH^-}$, your option 2.  

The difficulty arises because adding more $\ce{NaOH}$ to the reaction pulls off the second then the third hydrogen from the phosphoric acid.  In all cases it is an $\ce{H^+}$ reacting with an $\ce{OH^-}$ ion with the phosphate ions as spectators, but that really doesn't tell the story of the reaction well.  This is a case where the net ionic equation really isn't your best option.emphasized text