Can you suggest some treats that can be shipped overseas (and can last 10 days) ?

do not worry about cooked eggs and milks in cookies and stuff!!

only do solid cookies like sugar, shortbread, peanut butter, oatmeal, etc.

Do NOT do chocolate stuff unless it is a solid chocolate cookie. No fudge, truffles, etc. It gets too messy in the box.

pack this way!!
line box with plastic bag like a cooking bag for large roaster.
put a layer of popped popcorn without the butter, he can butter it later and packing is edible.
up sides of box a ways, layer the cookies in and cover each layer with popcorn, fill box to rim so nothing rattles with final layer of popcorn. Note: you could make caramel corn as it would travel well.

this way all but the box is edible and you wouldn't pay for non edible packing in the shipping cost.

I have shipped packages of this type since the beginning of the Viet Nam war! They get there fine!

Milk and eggs in cookies do not spoil, because they are cooked and because they are combined with a fair amount of sugar, which retards any spoilage. What's more likely is that they could get a bit stale after 10 days. Same goes for truffles, though I don't know what's in your truffle recipe. As long as it doesn't have raw eggs, they should be fine.

I've sent fudge any number of times from Canada to Germany, and no one ever complained that it arrived damaged. It's all in how you pack it. Wrap it well, put enough packing paper in the box so the contents can't move even when the box tumbles down a conveyor belt, and everything should get there fine. I wouldn't, however, try to send fragile or brittle cookies. Pick ones that tend to stay together, don't crumble easily.

I would make either a pie or cookies then after they are put what ever you bake out it in the freezer then wait two days then you can ship it over seas