How should the suffix of feminine surnames, e.g. Морозова, be considered from an etymological perspective?
Are -ов and -а etymologically distinct morphemes or parts of a single one?
It will be formed as the possessive form of a name or nickname:
Иван: Иванова дочь Марья. Мороз: Морозов сын Василий.
-а
is a distinct morpheme — an ending denoting case. The masculine nominative form is empty, but it becomes non-empty in other cases: (кому?) Иванову vs. Ивановой.