From my experience in the mental hospital, having visitors REALLY helps. Having family visit every day is what got me through my stay.
The mental hospital, contrary to expectations, is a very hostile environment to recover in. It's primary value is in seeing a doctor every day.
Being in one is a difficult ordeal to go through. Call the hospital and ask them when visitation hours are, and visit her now and then. If she's down when you see her or doesn't say much, don't take it personally.
You will only be a help to her, not a burden. Trust that.