I guess she wanted to get to the Lancelot's room sneaky using the key she has got. And she put on the socks as she wanted to look not so ladylike. But it's still not clear for me.
Answer:
"Little Stranger" is set in Warwickshire, England
Explanation:
I believe your answer would be 3).New.
The message throughout seems to be new, he even talks about feeling new.