<u>Judy can't drive and is married to the brother of the math teacher.</u>
So if she can't drive, she's not the truck driver, and she's not the math teacher if she's married to the math teacher's brother. (Unless-- let's not go there.) Judy is the housewife.
<u>Celia is the best friend of the truck driver.</u>
This mean's Celia's not the truck driver - and she's not the housewife, because we decided Judy was the housewife, so Celia is the math teacher.
By process of elimination, Betty is the truck driver.