Thelma Lou (Betty Lynn) in "Father Was a Fullback" with Fred MacMurray, Natalie Wood, and Maureen O'hara. This autographed photo is on sale on ebay at https://www.ebay.com/itm/Natalie-Wood-Betty-Lynn-autograph-VINTAGE-Photo-Father-Was-A-Fullback-/371331980234
Also, Betty Lynn played the voice in the same named Lux Theater radio drama. She played a teenager even though she was about 23 years old. Not my photo btw.