Who tried to kill this character in Mission Impossible: Fallout?

Ilsa Faust said:

“People have been sent here to kill Lark. Contractors. Paid assassins.”

And Alan Hunley said

If Lark isn't there in two hours the White Widow would sell the package to the highest bidder.

So we can assume these contractors and paid assassins were hired by countries/terrorist organizations to kill Lark so they could bid on the plutonium.

The wikia White Widow article (http://missionimpossible.wikia.com/wiki/White_Widow) is wrong, it says:

Ethan and Alanna (White Widow) learn that members of the Apostles, the remnants of the rogue Syndicate, are sent to kill them both and steal the plutonium.

This doesn't make sense because the Apostles already have the plutonium and arranged the meeting as part of their plan to frame Ethan Hunt as John Lark.

Faust was there to keep Lark alive for the reason that he'll be assigned/hired to kill Lane. But since Ethan compromised the plan, Faust was forced to kill Lark in the bathroom because Ethan is in danger of being shot.

That's why Faust was assigned to eliminate Lane since that's the price she needed to pay for saving Ethan.

So that's why it validates that the Apostles are the one who wanted John Lark dead.

The MI6 wanted Lane dead because he knew so much about the British government.

Henry's character is John Lark.

He might have lured Ethan into impersonating Lark because he knew that Lark's life might be in danger in that scene.

Ref, http://missionimpossible.wikia.com/wiki/August_Walker

Now about the question,

• The person who got killed in the washroom might be another guy impersonating as John Lark to meet White Widow and get hold of the plutonium plates & the person who wanted them.
• Remember, August hit that guy's head hard with the laptop that was to be used for creating the mask. Also, in one scene we see August getting a broken phone from this guy's pocket. But when he hands a phone to the CIA head it's clean as a new one.
• This all points sum up to August framing Ethan as John Lark to avoid from any threats that he might face.
• The guys sent to kill them in the club were supposedly from Apostle (or what's left of Syndicate) to finish John Lark & White Window and get the plutonium plates as well.

Ref - http://missionimpossible.wikia.com/wiki/White_Widow

Excerpt:

"Unable to create a mask of the man, Ethan assumes the Lark identity and meets with Alanna, hoping that they've never met in person. This proves to be true, but Ethan and Alanna learn that members of the Apostles, the remnants of the rogue Syndicate, are sent to kill them both and steal the plutonium. Ethan helps Alanna escape and continues impersonating Lark to acquire the plutonium. She provides a single core in good faith, but says her clients require the extraction of a political prisoner as the price for the two remaining cores. The prisoner is revealed to be Solomon Lane, the former MI6 agent who formed the Syndicate and whom Ethan and his IMF team captured two years earlier."

All of this was done to kill any person knowing of the entire deal, the dealer and getting the plutonium plates as well. Another article refers to that entire meeting being a hoax and main motive being to free Lane,

ref. - https://screenrant.com/mission-impossible-6-villains-explained-henry-cavill/

Excerpt:

"When the movie begins, it seems that John Lark has merely hired the Apostles to get their hands on some plutonium so that he can carry out some mass destruction. However, it turns out that the exchange is just a ruse to free Lane, and that both Walker and Lane are working towards the same goal - albeit with slightly different priorities."