This is sad... Prom is a big deal here and it's pricey. Some people are WAY overboard.. Your daughter did not have all the information when she made her choice to forgo prom.
That said, I wouldn't punish her just to spite that she's not doing what was agreed upon. Things change, especially in high school.
My daughter graduated HS in 2013. The dress she found for 2012 to attend with her bf from another school was way over the generous budget we gave her. She loved this Sherri Hill dress so much and it is gorgeous and looks beautiful on her.... So her compromise was to wear the same dress to her Sr prom. Her Bf went to a different school so as far as her friends were concerned, it was new!!
The group in 2012 split costs to have a party bus, I set up a special beautiful dinner within their budget at our country club with my connections. They all had a great time.
Move forward to 2013, she did not know if she was going to prom or not since she and bf broke up. Turns out that she did have a bf by prom time and we helped with professional pictures, dinner downtown Dallas and a private car for transportation.
I'd much prefer to pay for her and a friend or bf to have a limo or private car for the event. Safety is a key factor with that decision.
I did want her to have the momentos such as yearbook, homecoming, prom... She was on the cheer squad and Varsity Captain so she had leadership roles with the class of 1200+.
That said.. A class ring meant zero to her. So instead if purchasing an expensive class ring that would rarely worn, we purchased her favorite David Yurman ring for graduation... Probably less cost than a class ring!!! She wears that ring daily!!! It is way more special than a HS class ring to her.
So.... If my daughter had a friends with limited funds and she does... I have no problem footing the bill for momentos for her and her friend. We never expected reciprocation.... We wanted them to love this once in a lifetime event from high school. It is something we wanted to share with this friend.
Costs can be significantly reduced when groups share the bill. However, nothing was said or expected from this friend ( like your daughter) who benefited from the gestures. Her smile and happiness that evening was worth the extra money we spent. They are also still close friends!!
Try to look at it in an open minded way. Maybe someone is paying it forward to yiur daughter out if appreciation for her dad's service!!! I'd have no issue with doing that for a special girl.
Now... If there is an attitude with your daughter.... She needs to fix that stat before you consider any possibility. A snotty Attitude toward you is unacceptable!
Oh... And she has worn the dress again!!! It's unvelievably gorgeous and she'll wear it again!!!
Take care and thanks to your husband for his service.