Its a catch 22 situation. All the while you are there she is not considered "at risk" and because she is not at risk, SS wont offer help. I dont suggest that you pack your bags and leave, but perhaps you could step back in small ways. Get in carers and look at day care or respite. Perhaps you could make sure that the house is safe (switch off the oven etc) and install an alarm on the front door which will alert you if your mum opens it, so that there is unlikely to be a crisis, but might show that your mum cant cope.