My mother went through chemo in '03 and, thank God, she has been cancer-free since October of that year. She went through chemo and it was tough because she's in NY and I'm in Boston and my brother is in Maryland.
A few things helped --
1) I visited a few times, as I could, so did my brother. Just a few days. Even if all you do is the laundry, it means
a lot. She also came (with Dad, of course) to both of our homes and the diversion was extremely helpful.
2) My brother got her a subscription to a crossword puzzle magazine. You spend a lot of time waiting around and it helped pass the time. If your dear one doesn't like crosswords, perhaps a book club or just a few books are in order. DVDs/VHS tapes are fine, too, but for home. The books are for the waiting room. She might even like a Game Boy or music; does she have a Walkman? The things you want to do are: give her something to do while in the waiting room and also something to do at home when she's going to be mainly sedentary. These go a long way.
3) My mother's sense of smell became extremely acute; this was a part of the nausea. So I sent her some pot pourri packets, and that helped. If she got ill-feeling, she'd just grab the bag of peach-smelling stuff and it smelled okay to her.
4) Some foods are okay, some aren't. Mom was fine with Italian, but Chinese was no good. So we would go out for Italian, or cook it, when we saw her.
5) She will be tired a lot. Sometimes even just talking is going to tucker her out. Be prepared for this and don't overschedule. There's no problem with going to a museum, for example, if you make sure to only go to one or two exhibits and not the whole place, and bring the car around when the trip is done. A nice gift from the shop, to remember the trip, can be very special.
6) Mom got a wig, and I went with her when she got it. The people there were wonderful, and I helped her pick it out. I also got her an A2K hat and some kerchiefs for when she was just gardening or whatever and didn't feel like putting on the wig.
7) Irritability, like Noddy, said, may come with the territory. After all, it's no picnic. You will do best to be patient and assume that anything less than wonderful that is said or done is nothing that she really means to do. The more you can roll with the punches, the more she can.
She is lucky to have you.