[pushkar (OP)]

how is the repulsive force of electronic clouds surrounding each proton of two hydrogen atoms is overcome when hydrogen molecule is formed?

[lightarrow]

how is the repulsive force of electronic clouds surrounding each proton of two hydrogen atoms is overcome when hydrogen molecule is formed?

Because there is also the attractive force of each proton on the other atom's electron.

[Soul Surfer]

That's part of the story but it is much more complicated than this.  Protons and electrons also possess "spin" together with their electric charge and this makes them behave a bit like bar magnets.  now the electons keep the protons at arms length and so their spin does not have much effect (but it is very important and measurable) but electrons around atoms always like to be in pairs with their poles opposed (just like bar magnets) so the electrons on two single atoms of hydrogen end up with a pair of electrons around both protons with their spins opposed.