As a single dad I rarely let my boys go with anyone when they were little.
Especially after this one time they slept over a friends house on a friday night and I came to find out the mom of those boys went out dancing and left my sons alone with her boys in her house.
Lucky thing I was always as paranoid as I was because something told me to drive by the house and check on them around 10pm that night only to find them ALL alone. I immediately took them all back to my house.
And yeah, the mom caught a fucking earful from me and my boys never stayed there again.