"So, something's come up -- minor matter, almost nothing, don't worry about it -- but it means I need to take a little trip. You'll come along, won't you? We had so much fun last time, after all. And don't worry -- while getting to spend time with me is its own reward, I'm willing to throw in something extra to make it worth your while."
For an easier escort mission, try this technique : Cancel the escort quest at the notice board, travel to Bloodwater Beach (without Madeleine), deploy a Portcrystal, then Ferrystone back to Gran Soren. Accept the escort quest again and Ferrystone Madeleine directly to Bloodwater Beach in complete safety. Quest complete !