This is JMHO.
I have never had good luck with FTD types of orders, nor have I heard anyone who has. FTD is an 800- type number, who then call a florist in the area the flowers are to be delivered in and they place the order on your behalf. Flowers are such a regional thing - that when you place the order - you really won't have any idea of what the final product looks like unless the recipient takes a picture. Nor will you have an idea of how much your $50.00 (or what ever amount you choose) will buy.
My recommendation would be: do you know a good florist in the area your mom lives? (If you aren't familiar with florists where your mom lives - is there someone you can call?) Just call them directly, ask for what types of flowers they would recommend, state your preferences (i.e. fragrant, colors, one type of flower, a mixture of flower types). Give them your budget (be sure to tell them this needs to include delivery - I don't like surprises) and see what they could come up with.
Where we live, this time of year - irises - the deep purple ones with the bright yellow in the middle of the petals might be seasonal, and they look absolutely stunning with yellow roses.
You would be able to set this up with a florist in advance of your trip~unless you are leaving really soon.
I would just as soon skip the FTD fees.
Edited to add: I just noticed you are leaving in 7 days. Don't forget the florists are also dealing with mother's day flowers. I would get this taken care of ASAP, as opposed to waiting until right before you leave. Have a great trip - your mom will LOVE the flowers, regardless of what you have sent!