NSOR - interview thank you

[startingover2010]

I need to send a thank you note out, but I'm not sure how to do this one...I met with two ladies last week (one HR, one from the dept) but I only have the last name for the HR lady (I know, I should have asked for a card. But we ran out of time and I basically got kicked out so she could have her next interview!). So, do I

a) write one thank you note addressed to A and B and just mail it to A
b) address one envelope to A then have two small envelopes inside addressed to just the first name for each person
c) some other option that I'm not thinking of.

TIA!

[redredwine]

Find a way to get interview lady B's last name.
Send an individual thank you note to both.