A.B.
It probably is either an emotional problem, or more likely a stage that she will outgrow. My daughter went through something similar with going into my parents' garage. Just one day, all of a sudden, she was afraid. We just changed and entered house by front door. Might have been mistake, but we figured we have so many more years of other battles, that was probably the least of the ones to come. If she was terrified to be around grandparents or go into house at all, I would have questioned that. So, advice: Keep watching, and if you notice other behavior changes like regressed potty behavior, withdrawn attitude, loss of appetite and acting out aggression on toys and sibling, you will have to ring the bells and get the child some help. Meanwhile, if you have opportunity to spend time with her and help give her some stability, then do so. Otherwise, if you are not her guardian, there's little else you can do.