What a shame she canceled the night away. I would do a night at home with movies, popcorn, wine, snacks eg. If she wouldn’t mind a laugh, set up a home paint and sip. Kmart paints and so much fun

I think the the most precious thing you can give someone is your time, especially as they get older. Maybe a lovely lunch and show or whatever other thing she loves to do. Otherwise family pictures are always good gifts or maybe get a lovely family photo turned into a beautiful throw rug or something along those lines? My mum always appreciates a beautiful bunch of flowers as well.

I am sure she would just appreciate all her family to spend some quality time with her

A lovely high tea at a beautiful hotel is always lovely.
Maybe a weekend away rather to somewhere warmer like QLD..
Hope your mum has a special birthday.

Take her to the cinemas and a nice dinner

Is there something she might need help with and need your undivided attention to do.?

One of the greatest birthday presents is a child’s time and attention!

A lush dinner out maybe? Like a degustation dinner. And for the day maybe an art gallery or museum if that’s her interest, something special you can do together. It sounds like she might not be one for big celebrations so maybe keeping it low key.

What about a day out to a stage show or musical? maybe you could just actually ask her this time and let her choose.

Would your mum prefer a local restaurant or maybe a theatrical show?

I am 10 years younger then your Mum but find that I have everything I want or need and I know I am difficult for my daughters to buy for.
Perhaps have a professional photo taken of you and your children. Buy a nice frame a give that to her. This last Christmas i asked for a lovely framed photo of each of my daughters with their partners. They did an awesome job and now I have lovely photos to hang on my wall.