Which sentence is correct?

A. Is correct. 

The second sentence has two "woulds". You don't need two conditionals, to get the idea across.

HI 

you a head you'll be 

except

when you said

If they are both OK they you said they i thought you talking about sentences

Secondly may when you said

i'll be happy when you come . .. etc.

it's better than you know   

'I would be happy if you came' is correct. 

The second sentence contains two conditionals, would and would. 

Tip:  the formula for "contrary to fact" sentences is:  

[if + past tense verb] + conditional.   

This means there can't be TWO conditionals in the sentence.

I'd be happy if you came = I WOULD be happy if you came.  Correct.

I'd be happy if you would come = I WOULD be happy if you WOULD come. Incorrect.

Both statements are tentative, with no explicit request. Both tie to the topics of present and future perfect. This may help a bit:  https://www.mometrix.com/academy/present-perfect-p...   but if you're just learning English, you may want to postpone this topic until you have more experience, as this topic is mostly learned by exposure. Good luck.

I would say a.