Teach her an incompatible behavior, or in other words, a behavior she can not do while jumping up. For example, she cannot sit and jump up at the same time because they are incompatible. It sounds like you can easily predict when she is going to do this, so you should easily be able to set things up for success. She is old enough to use a prong collar on and she should be on leash whenever someone comes over or when you greet her. You will have to figure out all the details. You have to know how to correctly size the collar, put it on, and deliver a correction, after saying "no" "sit." When she sits, say "good sit" and reward her with praise, petting and a treat. Do this consistently and eventually she will default to sitting when she greets people. Never leave her collar on unsupervised.