How to tell my mom?

Due to covid only one person is allowed during delivery. My husband said that is him. Culturally it’s always the mother (so my mom). No one in my mom’s side or dad’s side had a spouse in the delivery room. That being said, I don’t mind my husband being there with me. Both him and my mom were there with my first and my mom ended up fainting and blacking out- she was moved to a different room and my husband was with me. Since then she was there for my cousin when she was delivering and she didn’t faint that time. Now my mom is coming from another state to be here for me for my delivery. She doesn’t know that the hospital will only allow one person. I don’t know how to tell her she won’t be there? Any advice? I think she is going to be mad. She was already kind of mad about it during my first pregnancy that she and my husband were going to be there, she just felt awkward she had said.