if you are backing use apple sauce or
if you like the taste of bannanas when you are baking then
you could use 1/4 cup bannana for the egg.
1 egg should be about 1/4 cup of what ever you substitute for it. I would not use the oil but thats just me.
good luck.How much olive oil needed to replace one egg?You cannot substitute olive oil for eggs. Tell us the recipe and we can give you a proper alternative ingredient. Hopefully. Just go get eggs.