Probably an affectionate alteration of mama or reduplication of mother.
Ma Maw is Lowland Scots for "My Mother". Ma is used when addressing ones own Mother, Maw is used when addressing others of ones own or others mothers ( aye yer maw, Glaswegian humour inferring disbelief with a hint of ridicule) Ma is also used to mean what is with you, what is beside you ( inferring ownership) when using both together, Ma Maw translates to My Mother.
mamaw (plural mamaws)
- UK `dialect `Scottish lowlands` one's mother.
- (US, dialect, Southern US) One's grandmother, especially one's maternal grandmother.
- (US, dialect, Southern US, less commonly) One's mother.