Our language needs a term like "curmudgeon" to refer to crabby, grumpy, crusty old men specifically because not all old men become crabby, grumpy and crusty. They are the exceptions.

There is no need for a female counterpart to "curmudgeon" because all old women do become crabby, grumpy and crusty. All that's needed is a word for the exceptional woman who somehow remains sweet, kind and endearing as she ages. "Mom" seems to work quite well.