Does anyone remember which episode of Sherlock the क्रिस्मस party, with Molly, was in?

That's the one with Irene Adler in it also...So, I think it would be "A स्कैंडल in Belgravia".

It was A स्कैंडल IN BELGRAVIA (S2E1).

Sherlock did not make a wrong deduction. Molly did have a crush on him. He correctly matched the neatness and red of the wrapping with Molly's lip colour. It was this incidence that helped him deduce that Irene Adler had feelings for him too (and she whipped him like the corpse in A Study In Pink.). He later confirmed this द्वारा taking her pulse and watching pupil dilation.