Which amongst the following options is the correct relation between change in enthalpy and change in internal energy?

By definition, $H=U+PV$. For a reaction involving ideal gases at constant temperature:
$$\Delta H=\Delta U+\Delta (PV)$$
Using the ideal gas law ($PV=nRT$):
$$\Delta H=\Delta U+\Delta n_{g}RT$$
where $\Delta n_g$ is the change in the number of moles of gaseous products and reactants.