What a dear you are to help this women at such a scary time.  I have gone thru one mascetomy and two lumpectomies so hopefully I can give some advise from my own experiences.  Depending on the location of the lump and the amount of tissue that needs to be taken will determine her amount of discomfort and recovery time.  Also, if her disabilities make her use her arms more than her legs for mobility, that will also impact her recovery.  Your medical team will be your best source of info.  After surgery you will have a better picture of what she will need.  I am sure you are already doing this, but if you feel her needs are not being addressed to the proper level  speak up, stand up and scream and yell if necessary. 

I did not feel that the lumpectomies were horrible, but they did cause a bit of discomfort for about 3-5 days, with soreness for about 10-14 days.  I cannot stress enough the importance of keeping meds onboard on a regular basis.  To let them wear out before you recognize the need for more will cause more discomfort than necessary. Once again, your med team will prescribe the best pain meds, but as your clients' advocate, if you feel they are not working, let them know.  There are many alternatives they can prescibe.

I hope I am not sounding negative.  I have had wonderful care throughout my years of treatment.  But I also know how busy our medical staff are, and every once in a while you will run into someone who just doesn't get it.  And I know how much I welcomed friends and family stepping in and fighting some of the battles so I did not need to.

So blessings and prayers to you and your client and her medical team.