some old people are senile. they have to look after like baby.
You are right that the old lady is probably senile. However, it is not right to treat them like babies,
It takes extreme anger to slap one's own mother. Such anger can be caused by the individual shitting everywhere, playing with shit, throwing or damaging valuable stuff.... Usually it started off with verbal threats or light slap to control the senile' behaviour. Slowly, as the illness got worse, so will be the violence.
Senile old folks cannot be disciplined like children. They won't understand a thing when the illness kicks in. Unlike children, a senile's fear, when threatened, is only for that moment and they will be back to their "mischieves" immediately. More frustrating, they can behave normally again all of a sudden. They can really drive the caregivers up the tree.