Stock her fridge, freezer and pantry with protein rich, healthy food.
Organise her friends to assist in any way they can - food, gardening, dog walking - whatever is a regular activity that requires energy she probably won't have. There are apps and websites for this kind of thing; check out mealtrain.com. Friends will want to help and it's much better when it's co-ordinated. Otherwise a lot of food can go to waste.
Sometimes partners need defined roles. Maybe put him in charge of one thing, like keeping track of her medications if that suits his personality. Reminding her to take her pills with a watch that beeps or somesuch.
Cleaning. If there is the money, organise for a cleaner to come in once a week or fortnight. If your mum qualifies maybe the council can help.
Does she like watching tv? If she does, and doesn't already have them, arrange a subscription to Netflix or Stan, or both!
Encourage her to walk daily, even just a little when she is most fatigued. It's been proven to relieve many of chemotherapy's side effects. Perhaps some friends can walk with her?
Make sure someone can drive her to and from chemo. Some people manage to drive themselves but I couldn't as I had to take drugs to counteract an allergic reaction that made me very drowsy.
She may not be receptive to these suggestions now but could be as the treatment approaches, or commences. She may be in a bit of denial, which is very common. Be mindful that the effects of chemotherapy are cumulative; what is mild in the first cycle can be severe in the last.
I was urged by every medico I came across to accept all offers of help. I didn't want to but realised I had to, so I did and it was of tremendous benefit. It has strengthened and deepened many of my friendships, a relieved the burden on my family.
Perhaps you could put it to your mother like this: if it was your friend who was having chemotherapy you'd want to do anything to make it easier for her, wouldn't you? People want to help, it makes them feel good. Why deny them the pleasure?!
Good luck with your mother, I hope you make some headway. Let us know how you get on.