What psychology and/or social work theories can be applied to the safety and well being of children for this scenario?

A call was received in the DFCS county office regarding the three McNulty children, ages 7, 5, and 3. An anonymous caller reported that the home these children live in with their mother and grandmother is very dirty with trash scattered all throughout the floor of the home and in the yard. The caller also reported that he believes there is little to no food in the home as the 7 and 5-year olds often come to his home asking for something to eat. All three children are often dirty when playing outside.