Most options for getting to the port are the same price for one person as they are for multiple people.
If you use a taxi or a town car it won't matter that she's only one person.
Probably using Disney transfers would be the cheapest option for her.
The Ron Jon resort looks great but if you were willing to spend the night at the airport instead, then all three of you could hire a town car together or rent a car and cut down on that expense.
I hope someone else has some better suggestions for you, good luck!