Questions From Employee

Just finding out my mother having neck surgery and its very critical. So i put in two week advanced notice for this to be put in as vacation time! Now my manager says i cannot take it because they are short staffed and when fully staffed i could take it, i tried callin my dm concerning this issue but he didnt answer so i texted him and still no answer! Is this legal or right because im sorry thats my MOTHER and surgery cannot be delayed! How do i go about getting this resolved or do i just need to quite! I have worked there for 6yrs and come to work when im suppose to and do what im suppose do!