My mom has stage 4 ckd and her dr. said she's not a canidate... what are the reasons they would deny her?

Dialysis?: I assume that your mother was turned down for dialysis. A nephrologist (n) may not give the patient refer a patient if the n does not think it would improve the quality of her life. Conditions such as severe dementia or terminal cancer would be some that would be causing the n to think she would not do well. Having said that, you can always seek a second opinion to see if another n agrees.