My dog is afraid of people in the house

If anyone can help me I would appreciate it so much. Nym is our black lab, she's almost 2 years old. Just recently she has become VERY afraid of anyone who comes in our house. I watch a 2 and 3 years old (have been since April) at first she was skittish and would just go in the bedroom. After a couple weeks she got used to the kids and was fine around them. Over the last few weeks she has become terrified of anyone coming into the house. When the kids get dropped off she hides behind the table until their mom leaves and it takes around 15 or 20 minutes for her to come out. She won't let the kids near her, she runs away when they walk past, gets off the couch if they sit down. The kids do need to work on personal space but they don't do anything to hurt her. They'll continue trying to pet her and hug her when she walks away (I'm working on teaching them boundries) When they get picked up, it's the same story, she hides until they all leave. Can anyone help me? Any tips or ideas to help her be more comfortable?