Because she promised them to Maggie when she marries John Thomas
"I promised to give them quilts to Maggie, for when she marries John Thomas"
The bold is from the story
Huckleberry Finn's character perfectly shows the spirit of the USA of that time. He is a commoner, uneducated and poor, with prejudice but not really sure of what he thinks and why he thinks it so.
Answer:
the guards are as a cold quiet night