The author of this topic last logged in several minutes before any replies, and she seemed patient (e.g., indicating that Mathilda still has to be TT into boxes), so Mathilda may still very well be available.
Oh, speaking of being careful with time stamps, I neglected that this topic was submitted several days ago. If you don't have any luck here, make sure to keep a close eye on other message boards, too, like GameFAQ and villagertrade.tumblr.
Moreover, at this forum, keep a watch of any "cycle" topic. Since Mathilda is not a popular villager, people offering villagers in those topics often "auto-void," which means you will have to request she be 'taken off auto-void' to make sure the author of the topic gives notification of when Mathilda is 'in boxes' or available for pick-up.