You. 

 (Sherlock meta by mae-jones)

Molly asks, “What do you need?”

Sherlock Answers, “You.”

Not, ‘your help’. Not, ‘help’. Not anything else.

Sherlock needed Molly, not just her assistance. I would argue there were agents Mycroft could have employed better than Molly. She was actually a huge liability and potentially detrimental to his plan. She’s not experienced in subterfuge. In fact, she wears her heart on her sleeve. I tend to doubt very much that she flitted around acting all cool and collected that day. Also, she would have been exhausted after pulling a double shift. Molly Hooper’s activities should have raised some serious red flags regardless of how ‘important’ anyone thought she was to Sherlock.

So, why did he risk it? He told us.

“You.”

He needed Molly Hooper. He wanted to be in the company of someone who loved him absolutely unreservedly in what might be the final hours of his life. He needed her emotional strength and support. He needed someone to save him while he saved others. No one else would do.