Then again, in a situation like this, you never can tell if you give out this wallet if they will still let you leave or treat you as trash after they get what they want. One thing is to ask for it, and the other is for them to keep their own side of the deal, so you have to take the risk involved here in order not to lose it all at once.
If there is some sort of guarantee that if you give out that wallet access to them, you will be set free, then the best thing will be for you to do that, as your safety and life matter more than that bitcoin. If you are alive and in good health, you can always acquire more.