Yep, mum here too. I even called my own mother mum while she was alive.
A funny story about "nanny". My mum hated being called nanny and asked to be called "granny Mona". DSS was only little, bless him, and had a "nanny glenis" and a "nanny wynne" and a "nanny sheila" and was struggling to grasp the concept of a different nomenclature so settled on "nanny grona". Fortunately, she saw the funny side and "nanny grona" she remained LOL