Hit and Run gives Mps after the attack resolves.

if Clawdite attacks Solo with hit and run and Solo plays Return Fire ,

which one plays first?

IF suppose Solo has the initat ive token...

Whether or not Han has initiative token has no effect here: the initiative thing only comes into effect when there's a conflict (like both abilities trigger "at the end of the round"). Here you follow the normal mission event -> attacker -> defender

Clawdite gets to use the 3MP before Han triggers Return Fire. There's also an existing ruling for eJet about being able to run away (with its bonus 2MP)

Not quite in this case the clawdite would gain the 3 mp into his pool but would be unable to spend them till after han returns fire. The ejet ruleing was to do with out of activation instances like emperor or call the vanguard etc

Movement points gained as a part of a special action must be spent immediately.

@ricope is correct.

The triggers for Return Fire and the movement points is the same, so they are resolved by attacker then defender.

Yep, basically the golden rule is that:

All movement points gained during your activation goes into a pool, but

if you gained them as from a special action (ex. playing Urgency during your activation) OR if you got them from out-of-activation abilities then you must spend them immediately

Also I forgot to clarify that yes the eJet ruling was a bit different because it was from call of vanguard (out-of-activation), eJet can't run away shooting Han Solo (and avoid return fire) during a normal round/gameplay

But i cant understand how this happens since the attack is RESOLVED, all the attack phases are over. So outside an attack the only thing that matters is who has the initiative token.

Oh!! found it in the latest FAQ ¨, although it still baffles me..... the attacker would resovle the 3mps first then han would shoot...

from the FAQ

"Any effects that trigger after an attack resolves use “during an attack” resolution order"

Yep, the latest FAQ clarified this