Help this is important

How many people is okay to live in a 3 bedroom 1.5 bathroom house. My neighbor has 9 kids and 4 adults so a total of 13 people in the house. The kids look like they barely eat, the kids clothes are always dirty and I don’t want to jump to conclusions and call DHS and get the police involved. I went to the mother and she told me mind my f***ng business all because I sent her youngest daughter some clothes and ask her why did her daughter have a big bruise on the back of her head I’m a nurse and I have a gut feeling that something isn’t sitting right. What can I do before contacting the police and DHS

Update I saw the bruise because my daughter and her daughter go to the same school. Her mom came late to pick her up and since I was walking to get my child from school she walked with me( it’s not the first time me and her child walk home together) she live 2 houses down from me. I asked her what happen and she told me my mom hit me really hard.