Balancing Ionic and Net Ionic equations
As $\ce{NaOH}$ and  $\ce{HCl}$ are strong base and acid respectively, they are completely dissociated in water. The salt $\ce{NaCl}$ is a  strong electrolyte and completely dissociated in water. So, the ionic equation is:

$\ce{(Na^+ +OH^- )}+\ce{(H^+ +Cl^- )}\rightarrow \ce{(Na^+ +Cl^- )}+\ce{H2O}  $

As the ions $\ce{Na^+}$ and$\ce{Cl^-}$ do not combine and remain in the solution as spectator ions. Their role is to keep the solution electrically neutral, the net ionic equation is:
$\ce{OH^- }+\ce{H^+ }\rightarrow \ce{H2O}  $.

On the other hand, we have to notice that the ion $\ce{H^+}$ is not stable in water, it combines with $\ce{H2O}  $ to form the ion hydronium $\ce{H_3O^+}$ . We usually write the complete dissociation of $\ce{HCl }$ as follows:

$\ce{HCl} +\ce{H_2O }\rightarrow$ $\ce{Cl^-} +\ce{H_3O^+}$

and the ionic equation is

$\ce{(Na^+ +OH^- )}+( \ce{H_3O^+}$$ +\ce{Cl^- })\rightarrow \ce{(Na^+ +Cl^- )}+2\ce{H2O}  $

And the net ionic equation is 

$\ce{OH^- }+\ce{H_3O^+ }\rightarrow 2\ce{H2O}  $.

As for your exam questions:
$2\ce{HNO_3} + \ce{Ca(OH)_2 }\rightarrow \ce{Ca(NO_3)_2} + 2\ce{H_2O}$
 Now you can try to write the ionic and the net ionic equation to see if you understand what I have explained.