Molly says the first two don't count. They were meant as an apology and a sort of goodbye. Besides, they were on the cheek.
Sherlock maintains that they were both sincere and, although he didn't consciously realize at the time, they were also both romantic in nature and therefore they do count.
John refuses to arbitrate, as does Lestrade. They don't even consider asking Mycroft and Sherlock knows Meena will side with Molly so he nixes that idea in the bud. Then he has to apologize to Molly because he nixed it in the bud before she even drew breath to suggest it and she hates it when he does that, cuts her off before the words do more than form in her mind. That kiss, unquestionably, is romantic and apologetic, quite consciously so. But it's not in the running because it's their seventeenth kiss (by his counting, fifteenth by hers and thus their ongoing conundrum).
Mrs. Hudson is chosen as the final court of appeals, after Sherlock (allowing Molly to actually make the suggestion out loud this time) claims that his parents would be just as biased as Meena. Biased towards Molly, not their own son, as they adore her and won't hear a word against her. (Not that anyone tries, certainly not Mycroft after receiving a lovely shiner because of some snide comment he'd made that Molly shrugged off but Sherlock…well, he's awfully proud of that shiner.)
"Oh, love, sorry, but I'm with Molly. Those first two don't count. I mean, yes, they were kisses and very sweet ones, at least the one I saw you give her - oh, and wasn't that unexpected! Molly, did you know we'd none of us ever heard him sincerely apologize to anyone like that before? Not even me, and I've known him longest, never mind what Greg claims. He's a dear boy but a bit forgetful at times."
Sherlock's eyes sort of glaze over midway through Mrs. Hudson's speech but Molly is grinning and squeezing his hand the entire time. When she falls silent, beaming at the two of them as if she were some benevolent goddess offering her blessing (and in a way, that's exactly what she's doing, at least in Molly's mind), Sherlock huffs out an annoyed breath. But he's agreed that Mrs. Hudson has the last word on the subject and so he shrugs and offers Molly a smile of his own.
"Fine," he says, pulling her close to his side, his arm around her shoulder. "The first kiss was the one we shared in your flat after I explained about Eurus and you patched up my splintered hands and told me what an ass I was."
"Bastard," Molly corrects him, her grin widening. "I've never called you an ass." She turns her smile on Mrs. Hudson. "Thank you. He may be clever but sometimes he just doesn't get it."
And Mrs. Hudson nods in agreement, then heads back down to her own flat, leaving the two love-birds to add to their growing stockpile of kisses.
Now if only those kisses could lead to grand-tenants, her life would be complete.