What is a "suvivorship"?

You need to know accounts, banks and account numbers. Were Mom to pass the banks will NOT notify you you are POD or "survivor". They do have your SS number in most cases so you might find out round the bend, but in most cases you would not. This is a HUGE mistake made by many and this money is then just sitting in state's coffers as unclaimed money.
Being POD, TOD, or Suvivor means that the account is titled Alva Deer, Baby Deer POD. That means that the day that I die this account BELONGS TO baby deer and all baby deer has to do is go into the bank or deliver if online banking an original death certificate and the account is transferred to baby deer in whole. And yes, there is good reason to put POD on all accounts if she has a simple will. She can decide with one CD who gets what. The accounts do not go through probate at all. They are simply yours. In fact they are currently covered as two owners for FDIC insurance. So they can be not only 250,000 per institution, but 500,000. So do tell Mom THANKS, but I need to know WHAT ACCOUNTS and I need a copy of them and the banks papers or the bank will never let me know this money is mine.

If your mother doesn’t have you listed on her account as joint, and only as POD, you can’t touch the funds until her death and a death certificate is available. Perhaps a different length of time where you live, in my area, a couple of weeks. That may or may not be important to you. If she is in the hospital or incapacitated and you want to access her accounts to pay her bills, a bit more trouble if you aren’t on the account as joint. If she has all her accounts assigned as POD or joint and her property deeded to you, then you may not need to probate her will. It depends on your state. Just because you are her only heir is not always the only governing factor. Check with your certified elder attorney or other legal or financial counsel before you advise your mother to change anything. Good that you are looking into it.

Joint means that the account is equally yours and you can do business on it. It can be messy with a still living Mom as when she applies for medicaid this accounts for her assets and yours. POD is beneficiary. The account is yours upon her death and a death certificate presented gets you the account that very day. POD (pay on death) is survivorship. Joint is co-owner ship with all rights.