As you say your mum will be starting Chemotherapy when well enough, Chemo affects people differently, some have minimal effects while others feel it, try and get Mum not to go to chemo expecting the worst
When she starts it will be explained what she can possibly expect from the treatment, if you have questions along the way try and have them written in note form as it can be stressful and you can forget to ask what you have planned to.ask the Oncologist ,good luck with her treatment, it is a very stressfull period in all your lives.
You must look after your self as well.
kj