Assalaamu alaykum. A non-Muslim is saying that it is reported in Ibn Hishaam 166 that when the Prophet, sallallaahu 'alayhi wa sallam, was born, light was coming out of the vagina of Aaminah. Also, what kind of respectable suffix should we add before the names of the parents of the Prophet; should we write "Hazrat"?

All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger. 

It was reported in some narrations that there was light in the vicinity of his birth and some narrations state that the palaces of Shaam (the Levant/Greater Syria) were lit because of his birth.

Ibn Hajar said in Fat'h Al-Baari:

“Among the signs of his Prophecy that appeared at his birth and after his birth was what At-Tabaraani narrated from 'Uthmaan ibn Abi Al-‘Aas Ath-Thaqafi, from his mother, that she went to Aaminah, the mother of the Prophet and she related that when she [Aaminah] was in labor (i.e. giving birth), ‘I was looking at the stars getting closer to me to the point that I thought they would fall on me; and when she gave birth, a light came out of her that lit the whole house.’”

This hadeeth is supported by another hadeeth narrated by Al-Irbaadh ibn Saariyah, who said:

“I heard the Prophet say, ‘(Allah has written in the Preserved book) that I am the Slave of Allah and the Seal of the Prophets while Adam was not yet created. I will inform you about that: I am (the result of) the supplication of my father Ibraaheem (Abraham), the glad tiding given about me by ‘Eesa (Jesus), and the vision which my mother saw – like what all the mothers of Prophets see – and that when the mother of the Prophet gave birth to him, she saw a light that lit up the palaces of the Levant.” [Ahmad - Ibn Hibbaan and Al-Haakim graded it saheeh (sound)]

The same thing was mentioned in the hadeeth of Abu Umaamah that was reported by Ahmad, and Ibn Ishaq reported the same thing from Thawr ibn Yazeed, from Khaalid Ibn Ma'daan, from the Companions of the Prophet and she said, “Busra in the land of the Levant lit up for it (for his light).”

In Al-Bidaayah wan-Nihaayah, Ibn Katheer, after mentioning some of these accounts, said, “These narrations necessitate that when she was pregnant with him, she had a dream that light came out of her that lit the palaces of the Levant, and when she gave birth to him, she saw with her own eyes the realization of this dream, just as she had seen it before that.”

There is no title that we must use when we mention the parents of the Prophet neither the word "Hazrat" nor anything else.

We have found that when the scholars of biography and the like speak about the Prophet's parents, they mention them by stating their names and family names without using any title before their names.

Allah knows best.