Sorahana
Trying to put in specific medical information makes the story unrealistic and distracts from the story. Getting a kidney transplant has a lot more concerns than just money. There is the issue of locating a kidney donor that matches, blood type, etc. If daughter donated kidney before, she only has one left. Where are they getting another one? Also, since mother already got one, doctors would view mother as higher risk so would likely put her further down the list of receiving a kidney transplant.