So a few things,
Not normal for a child to be too scared to ask their mum when there's a bloody power outage. I've been ill recently, often flake out if I sit down, DD would still come and talk to me if there was a problem with the power (has been a few issues, water was off for routine maintenance a few wks ago, have lost power and Internet due to cables on local building projects, all times I've either shouted to her, usually something like Is your Internet off? Switch your phone to WiFi or have you lost power too?!
General normal stuff, but this is how parents and their kids are expected to communicate in these type of situations. Not to be scared but not feel you can turn to your mother at that moment.
What you mention about this child's general personality id worry too.
I also want to say, social services come in, offer support if you need it, then they go. Its highly unlikely that this child is on anyone but maybe the teacher from todays radar.
I get that she has MH issues, and I'd maybe excuse one instance of thinking, she's stressed, she's struggling, ok I can understand x/y/z but the bigger picture seems to be that this child is;
Nervous,
Scared,
Unable to turn to his mother in times where he should be given some sort of reassurance and care (we all know how our kids will deal with a bump in the road, and you act accordingly don't you?),
You've seen her regularly stressed,
You've seen her be a bit rough with her toddler.
Theres a few of you obviously concerned. Please report. If you don't feel comfortable doing so, speak with the teacher who was in the lesson you heard.