That is way to much dog for that girl to handle.
He knows she is not the boss . I love Mastiffs and none of mine would have dared climb on my bed or any furniture in my house more than once .
They are adamant that the master/alpha's sleeping area (i.e. bed) is reserved exclusively for the alpha. I'll occasionally call my dog to hop up on here (especially on cold nights), but he won't come without permission, and is normally reluctant to stay for any length of time. He knows that if he ever challenged me for it, he'd catch hell.
This lady is basically training her dog to defy her.
I love the Mastiff too. They are dominant and pushy if you let them. She and the dog need training.