When Mason got back home that evening, Ava wasn't there, she had sent him a text earlier saying she was going out with Maddie to help her shop for a dress.
Mason was happy that she wasn't allowing the return of her mother to hamper her from going out. He feared she might decide to remain indoors trying to hide from her mother.
He thought of getting her a bodyguard to help her feel safer but Ava had refused and he didn't want to argue with her, so he allowed her to think that he had backed down on the idea but he hasn't, he was already talking to Stan about helping him get a bodyguard for her.
Even if her mother was just some Crack head, he doesn't want to take any chances with her safety. There is no telling how far these people can go just to get a fix.