Acting out when MIL is here?

So my almost 2 year old got sick last Wednesday. Stayed home Thursday, Friday, the weekend of course and Monday. He’s been with my MIL all this time. She’s staying with us and has been here a week. He is being SO bad. He’s hitting me and biting me and will not listen. Keeps saying no. Granted he had some attitude before all this but no where NEAR as bad as this. Has anyone had this problem? I just want her to leave so he goes back to normal. Unless this is his new normal but I feel like it’s because she’s here.