That is certainly a possibility but that’s not indicated. All we know is that she didn’t come home after work on a dark and rainy night. The grandparents, even if the shittiest grandparents ever, called around looking for her. When they didn’t find her, they called the police. I am still not understanding the problem here. OP even admits that they don’t do this to her often. They do monitor their drug-addicted daughter a lot more. Because she is an addict who is living with them. Should they just not care what their daughter and grand daughter are doing or where they are?