Here is a situation you might not have considered:
You give the woman a CD with a few digital files (even small-ish files at 600 x 800 pixels).
Six months from now a "friend" of the woman mentions to her that they need photos from the track day . . .
The woman you gave the CD to doesn't know anything about intellectual property laws, copyright or trademark issues so she says to the friend, "hey I have a CD with pictures on it you can have" and, as it turns out the friend is the owner of the riding school.
The "friend" uses the pictures in an advertisement that is printed in several magazine issues, a billboard on the side of the freeway and several banners displayed at the track advertising the riding school . . .
The woman knows nothing about intellectual property laws, so she has no idea she did something wrong . . .
The "friend" who owns the riding school also has no clue about copyright and intellectual property laws, so that person has no idea that what they did was wrong . . .
Nobody cares WHO took the pictures, only that the woman in the pictures is someone they know . . .
Meanwhile you DIDN'T get paid a single cent, or the woman paid you $40 bucks for the CD and you are left trying to explain to the people that YOU didn't give permission to use your images in advertisements and you would like to be paid a reasonable amount for the licensing of your images . . .
You should have thousands of dollars in your pocket for the use of your images, but the hassle of trying to educate these people about intellectual property laws just sucks-the-life out of you and your creative spirit, blah, blah, blah.
Or . . .
She gives you a few bucks for the CD and makes a few prints for her garage and everyone is happy . . .
You just never know how these things are going to work out . . .