As $\mathrm{L}{\mathrm{i}}^{+}$ and $\mathrm{B}{\mathrm{e}}^{2+}$ both have 2 electrons so they are iso electronic. Rest other ions have different number of electrons than $\mathrm{B}{\mathrm{e}}^{2+}$ so there is no relation between them. $\mathrm{N}{\mathrm{a}}^{+}$ , $\mathrm{M}{\mathrm{g}}^{2+}$ both have 10 electrons.