Check option A: HF is less polar than HBr

Polarity depends on electronegativity difference.

• Electronegativity of $F$ is much higher than that of $H$.
• Electronegativity of $Br$ is lower than that of $F$.

Therefore, the bond in $HF$ has a greater electronegativity difference than in $HBr$, so $HF$ is more polar, not less polar.

Hence, A is false.

Check option B: absolutely pure water does not contain any ions

Even absolutely pure water undergoes self-ionization: $2H_2O \rightleftharpoons H_3O^+ + OH^-$

So pure water contains a very small concentration of ions.

Hence, B is false.

Check option C: chemical bond formation takes place when forces of attraction overcome the forces of repulsion

A chemical bond forms when the net attractive interactions between atoms lower the energy of the system.

In bond formation:

• nucleus-electron attractions act,
• electron-electron and nucleus-nucleus repulsions also act,
• bond forms only when attraction dominates sufficiently to give a lower-energy stable arrangement.

Hence, C is true.

Check option D: in covalency transference of electron takes place

In a covalent bond, electrons are shared, not transferred.

Electron transfer is characteristic of ionic bonding.

Hence, D is false.

Conclusion

The only true statement is: $\boxed{\text{C}}$