Nervous Pup

I really need help. We got an 1 year old American Foxhound puppy in November. She is sweet as can be but she is afraid of my in laws. So much she shakes when they’re and barks at them when they get home. She has gotten closer with mil but she is still on edge around her. The issue is that it has come to her refusing to go downstairs when they’re in the kitchen and ends up going to the bathroom on the carpet upstairs. Outside of these moments she perfectly potty trained. When they aren’t home she comes and goes out through the doggy door just fine and no accidents. I don’t know what to do because I have walked her down on leash or even carried her down to go out when they’re downstairs and she anxiously runs back to me .