Losing concentration on Conjure Elemental if you summon an Invisible Stalker?

Question

So basically, say I use conjure elemental as a 6th level spell and summon an invisible stalker. I give it an order to kill the BBEG our party is fighting. I then take a hit and lose concentration. There are 3 possibilities that might happen:

1. as the spell says, you lose control of the elemental and it may attack the party.
2. due to the invisible stalker's page in the Monster Manual (pg. 192) under "Directed Hunter" it disappears due to the line "... forced to serve until the magic that binds it expires." (emphasis added)
3. because of the line also under "Directed Hunter", "If its summoner dies in the interim, the invisible stalker vanishes after completing its task." (emphasis added) one might assume that death would break concentration of a spell. This might imply that if a command is given to an invisible stalker and then the summoner loses concentration that the invisible stalker would continue to carry out its task before either disappearing OR turning on the party (AKA completing the task and then referring to 1 or 2).

What would be considered the outcome in this situation?

Answer 1

If you break concentration it becomes hostile and might attack you

From the invisible stalker entry under Directed Hunter, "...forced to serve until the magic that binds it expires". The magic that binds it is Conjure Elemental and when you lose concentration that magic expires.

Then we go to Conjure Elemental which says, "...you lose control of the elemental, it becomes hostile...and it might attack", so that happens.

If you die it becomes hostile, and could attack you, but instead just finishes its task and leaves

In a nice case of specific beats general the invisible stalker entry says, "If the summoner dies in the interim, the invisible stalker vanishes after completing its task". So if you manage to die without first breaking concentration for another reason (say from massive damage) the invisible stalker will finish what you asked of it.