The following are the statements regarding polarizing power of IIA group cations 

i) $\mathrm{Be}$ always forms covalent compounds due to high polarizing power of ${\mathrm{Be}}^{2+}$ ions 

ii) $\mathrm{Be}$ always form covalent compounds due to low polarizing power of ${\mathrm{Be}}^{2+}$ions 

iii) Polarizing power of IIA cations decreases from ${\mathrm{Be}}^{2+}$ ion to ${\mathrm{Ba}}^{2+}$ ion 

The correct combination is 

• Beryllium is an IIA group element having small size. And the polarizing power of $\mathrm{Be}$ is high due to its small size hence is more covalent in nature. Covalent compounds are formed due to high polarizing power of Be not low.

And we know, larger the size of cation, lower is the polarizing power. As, the size of ${\mathrm{Be}}^{+2}<{\mathrm{Ba}}^{+2}$ hence, the polarizing power decreases from ${\mathrm{Be}}^{+2}$ to ${\mathrm{Ba}}^{+2}$. So, the option $\mathrm{i}$ and iii are correct.

Therefore, option (C) is correct.