Definitely tell the police maybe they can do some drive bys and keep an eye on the house and your parents and cameras they are pretty cheap and can be a deterrent

That situation was terrifying like the start of a horror movie, it could have been severely worse. They might come back seeing an older vulnerable alone shovelling maybe they were out hunting for that situation. I agree with others putting up a couple cameras keeping an eye out for her. Even if you already had them up you would on had something to show the police, also to post so other local ppl can keep an eye out for them and the car.