Substitute for vegetable oil in brownies
Any fat can always replace any other fat, so if you have any of the following around, they can be used as a substitute:


Butter
Duck fat
Olive oil (yes, it's a vegetable oil, which you say you don't have, but you might not have thought of this one)
...


Note however, that using different fats will change the texture and taste of the final product. (if you're used to very soft brownies, butter will give you a less soft experience and duck fat will change the taste)