Medications making my dad zombie like!

That's quite a cocktail, but my understanding is that the aim is to stabilise people in emotional distress -- which inevitably means quite heavy sedation -- then reduce medication to where the benefits outweigh the disadvantages.

It is, as I know from trying to manage my mother's extreme distress in the early years, a far from perfect process, because dementia is a far from perfectly understood disease.

I hope your father's situation improves soon.