Yes, this is a common symptom of dementia. People with dementia can become irritable and agitated very quickly, and it’s exacerbated, in this case, by the fact that she probably knows she’s struggling with her memory and it makes her mad. Knowing Klonopin, I feel like it would just make her tired and numb, but I suppose it could be that. Unfortunately (as long as it’s not the Klonopin, check with a doctor) you have to just grin and bear it when she talks like that. She will probably stop talking like this at some point soon. Remember not to fight back or argue, just separate yourself and let her calm down.