Portable treat for Latino or Hispanic family

Sorry, can only offer perishables. I suggest pasteles en masa, a meat or bean concoction wrapped in dough. Delicioso, and typical homemade dish for picnics, outings, etc. Popular in Latin America, PR, and elsewhere en el caribe.

--RAMAHLite

A box of flan....

empanaditas .... a fruit pastry made with a circle of dough folded over a fruit filling. Much like a Cornish pastie, but with fruit.

They aren't much for baking in AZ or Mexico, because the Mexican bakeries are really good, and cheap.

Dulce de leche, perhaps?

If the family is from Argentina or Uruguay: alfajor, probably. a kind of a small sandwich made of a sweet dough with dulce de leche between then. Sometimes, covered with chocolate. A poor family would probably skip such covering.

If from Brazil: In the south and central part of Brazil, the choices would probably be "bolinho de chuva" ("rain little cake"). Small (enough to fill a regular spoon)portions of a sweet dough mixed with baked banana and, aftwards, covered with sugar and cinammon. Now I'm hungry.
That, or "biscoito de polvilho". A small, white cookie made with milk and the starch of tapioca (cassava, manioc). That would really nonpereshable. I'm even more hungry.
Now, at the north/northeast of Brazil, the choice would be "rapadura". It's a compact mass made of sugar cane and cut in candybar shapes. It's very hard to bite and very sweet. Also extremelly durable.

Of course, if you choose those brazilian treats, your family would not speak Spanish.
Hope that helps.