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.