Greenwood may have suffered from child abuse.
This could be why she had been brutally bullying Mai. Mai’s father began drinking himself to death after losing everything.
Given how prevalent robots are in the film (even individual disposable ramen bowls are robots!), it's entirely possible Mai's father was one of many laborers who most likely lost his job to robots that could do it better for free, so he turned to alcoholism to cope, causing a rift between him and his wife that eventually grew to the point he ran out on her and Mai forever. Ares might have installed a lot of cameras all over the community and entered with stealth.
Seeing as how Justin Pin entered the house without knocking at the door, and followed Dr. Rice, it must be because of stealth and has surveillance everywhere.