Often, if a recipe only wants an egg or two, you can omit the egg. Be sure to add a bit more liquid to it though, to keep things balanced.

Perhaps someone in your home has an allergy to eggs, in that case a full substitution will be needed.

1 egg = :

1/2 banana

or

1/4 cup applesauce

There are others i am sure, but those are the ones i know. Perhaps your dietician can recommend others. As far as i know theres no commercial soulutions available, as there is for items like milk.