Mother's Day in Dublin: daffodil weeks and a bouquet made to order
Mother's Day in Dublin falls on Mothering Sunday, the fourth Sunday in Lent, three weeks before Easter, in the very weeks when Ireland's flower farmers, County Dublin growers among them, are out cutting daffodils. The bouquet she receives draws on the same season's greenhouse flowers alongside stems brought in from further afield, and the choice comes down to the flowers and the format.
Irish daffodils outside, greenhouse lilies and roses in her bouquet
Spring in Ireland means daffodils in the ground. More than a hundred growers belong to Flower Farmers of Ireland, among them nurseries in County Dublin, and daffodils are what they're cutting at this time of year. Home-grown cut flowers remain a small part of what Dublin florists sell, though, and most of the stems in a bouquet have travelled further than any Dublin field.
The main supply route runs through the Netherlands, with further shipments from Kenya, Colombia, Ecuador and the UK. That is where much of Dublin's cut-flower supply comes from, whatever is or isn't flowering outside the window.
The flower stalls on Grafton Street keep roses, lilies and tulips on sale all year; peonies and hydrangea only join them once summer arrives. Lilies, gerberas and lisianthus, by contrast, are greenhouse flowers grown under glass year-round, which is why they form the backbone of a Mothering Sunday bouquet regardless of the date. Lisianthus in particular softens a rose, and a bouquet of Roses with Lisianthus pairs the two, which makes the roses feel less formal.
If daffodils from her own garden are already standing in a vase, give them a day in water on their own first, then stand them beside the new bouquet without recutting either one.

Wrapped stems for her vase or soaked foam for her table
A wrapped, spiral-tied bouquet is built to stand on its own once it's in her vase, with no extra support needed. A box or a basket works differently: the stems sit in wet floral foam, and the arrangement never needs a vase at all, which makes either one the easier gift if she doesn't own one worth using.
Foam needs watering every day, over its whole visible surface, and the arrangement should never be tilted while that happens. Left to dry out, foam barely takes water back in; kept properly watered, it holds a bouquet for roughly as long as a vase would. A potted plant is also on offer, a gift that keeps going without any promise on how long.
More on what what Dublin's weather means for cut flowers is covered on that page.

Three weeks before Easter: Mother's Day flower delivery in Dublin
The date moves every year with Lent and Easter, and the May date some are used to from the US isn't marked in Ireland, so it's worth checking a calendar rather than a habit.
The delivery page names Mother's Day as one of the days when order numbers run far above normal: booking ahead matters, delivery windows run wider than usual, and no courier promises an exact minute. Date and time slot are both chosen at checkout, for any part of the city, and the earlier the order goes in, the more slots are still open.
Most bouquets are delivered the same day they're ordered, and the time frame for any one bouquet shows on its own page. A photo of the finished bouquet goes out before the courier leaves, the recipient isn't called ahead unless the sender asks for it, and delivery within the centre is free.
A good place to start is by format: mixed bouquets wrapped for her vase, flowers in boxes that need no vase at all, and flower baskets built the same way on wet foam.