Write the net balanced ionic equation for the Fe metal with HCl in the absence of air.

Both mass and charge must be balanced in net ionic equations. Balancing by mass implies that the total mass of reactants is equal to the total mass of products. Balancing by charge entails ensuring that the overall charge on both sides of the equation is the same. 

To write the net ionic equation for the unbalanced reaction, we must first be able to distinguish between strong electrolytes, weak electrolytes, and insoluble compounds. In water, strong electrolytes completely dissociate into their ions. Weak electrolytes produce very few ions in solution, so their molecular formula is used to represent them.

Iron$\left(\mathrm{Fe}\right)$ reacts with Hydrochloric acid $\left(\mathrm{HCl}\right)$ in the absence of air. 

Thus, the net balanced ionic reaction is $\mathrm{Fe}+2{\mathrm{H}}^{+}\to 2{\mathrm{Fe}}^{2+}+{\mathrm{H}}_2$.

Hence, the correct option is (B).