I have been sectioned and an IP for being suicidal/psychotic. Visits were always welcome to break up the day.
Things to take: magazines, chocolates/sweets, crisps, basically snacky type foods, small bottles of drink (easy to carry round), colouring in books and nice pens/pencils, a nice notebook and pens, smellies... I like to paint my nails so friends brought me in polishes and nail bits which were much appreciated. I also sew so sewing magazines and kits were welcome. It of course depends on her and what she is feeling up to. Just little things that break the day up help. Oh and if she feels like it bring her in a sandwich or MacDonalds or KFC or something, my friend used to being me in a MacDs on a Thursday and it was lovely.
If she smokes then take in some cigarettes for her - this for me was the most important thing, having enough cigarettes. I used to ask for cigs and diet coke when people asked what to bring!
And just talk about normal stuff. The TV, work, friends, life, don't worry about making her worse or anything like that.
Don't take lighters, wires/scarves (chargers etc), sharp things (nail scissors, metal nail files).
Oh and being sectioned doesn't mean you can't leave the ward, you can have leave to go out with friends and family so while she may not be able to go out at the moment when she does get leave then take her out for a coffee or a little shop, it makes such a difference.
Anything else just pm me :)