If my granny slips her 9mm into the seat of her walker, does she need a concealed handgun permit?

Yes of course she's hiding it.

to start "the rules in your state or county may be different than mine please check all state and local laws before using my advice where you live"

the chances are that it would be considered concealed carry as you stated it is loaded and it is concealed in her walker. your mileage may vary however this is the general rule of thumb

side note if it is not "readily available" than what good is carrying it in the first place she would be better off getting the permit (costs about $100 where i am) and know that she would not be in trouble regardless. (if she is banking on her age to protect her, the police are cracking down on the elderly for such infractions.)

Call your local sheriff's office and ask, not 911. We've no way of knowing what the laws are that apply in your location.

Not legal, and they jail grannies too.

If it's in a walker, it's "within reach ".

John, step up and pay for her permit.

:-)