Remember what she actually likes
There is no required “mother” flower or palette. Think about what she keeps at home, which colours she chooses for herself and whether she enjoys compact or expressive arrangements. Her taste carries more meaning than a ready-made seasonal symbol.
Consider practicality: bouquet weight, the height of her vases and whether she will need to move the gift. If she is sensitive to strong scents or has particular flower preferences, add that information to the order note.