Does scolding and reprimanding an elderly grandmother—who is not aware of her actions—invalidate the reward for serving the sick?

Whoever reaches a state of not being aware of their actions, like the grandmother, is excused. One must be patient with her and seek reward by serving her. It is not permissible to scold or reprimand her. Serving the grandmother is rewarded if one seeks the reward for it, and if one wrongs her, then he must repent. His wrongdoing does not invalidate the reward for the service.