How often should narc grandma see grandkids

My husband and I have a 13 month old. My husband’s mom is a clear as day narcissist. She is divorced, and solely revolves her life around her adult and married children. She burned the bridge with me and her other daughter in law, to where we don’t feel comfortable alone with her. My husband isn’t comfortable around her much either. She always has some drama, or woe is me manipulation, or lies constantly. We keep her at arms length.

My husband tries to have her see our son for a few hours once a week, typically on the weekend because he works M-F. If we can’t make that work (like if we get sick and have to cancel with her/ push it back) she usually tries to make us feel guilty one way or another.

My parents live in a different state so I don’t know the norm here. Is once a week too little? Or are we being pretty generous?