"Grandfather does not eat apples."
Translation:नाना सेब नहीं खाते ।
Am I correct that the े ending is due to respect? Otherwise it would be ा? Would you automatically use े for anyone older?
You're right. The complete sentence would be - नाना सेब नहीं खाते हैं।
I suggest you not to skip the हैं. And yes, most Hindi speakers automatically speak like this when talking to someone older than them. But at the same time, you wouldn't be technically wrong for not using the honorific.