If Prostration is allowed to someone other than Allah then it would be to husband - NikahExplorer
Allah has created the husband the protector and the most responsible person in the relationship of Nikah. Husband is better in rational thinking than the wife in many cases. This means that it is obligatory for her to obey him. The position of a husband in the bond of marriage is made in such a way that his wife must obey her and he should also aware of the responsibilities which are assigned to him by Allah.
Allah says in Surah An-Nisa, Verse: 34
"Men are in charge of women by [right of] what Allah has given one over the other and what they spend [for maintenance] from their wealth. So righteous women are devoutly obedient, guarding in [the husband's] absence what Allah would have them guard. But those [wives] from whom you fear arrogance - [first] advise them; [then if they persist], forsake them in bed; and [finally], strike them. But if they obey you [once more], seek no means against them. Indeed, Allah is ever Exalted and Grand".
Our beloved Prophet, Hazrat Mohammad (P.B.U.H) said that if it would be allowed to prostrate someone then he (Prophet Mohammad) would instruct the wife to prostrate to her husband.
Ibn Hibbaan (4162) narrated from Abu Hurayrah that the Messenger of Allah (blessings and peace of Allah be upon him) entered one of the gardens of the Ansaar, where he saw two restless camels. The Messenger of Allah (blessings and peace of Allah be upon him) draw close to them and they knelt down and lay their necks on the ground. Those who were with him said: They have prostrated to him. The Messenger of Allah (blessings and peace of Allah be upon him) said: “It is not appropriate for anyone to prostrate to anyone else. If it were appropriate for anyone to prostrate to anyone else, I would have instructed the wife to prostrate to her husband, because of the great rights that Allah has given him over her.”
Abu Dawood (2140) and al-Haakim (2763) narrated that Qays ibn Saad (may Allah be pleased with him) said: I went to al-Heerah and saw them prostrating to a noble of theirs (i.e., a courageous knight who was prominent among them). I thought: The Messenger of Allah (blessings and peace of Allah be upon him) is more deserving that people should prostrate to him. So, I came to the Messenger of Allah (blessings and peace of Allah be upon him) and said: I went to al-Heerah and saw them prostrating to a noble of theirs, but you are the Messenger of Allah (blessings and peace of Allah be upon him) and are more deserving that people should prostrate to you. He said: “Do not do that. If I were to instruct anyone to prostrate to anyone, I would have instructed women to prostrate to their husbands, because of the rights that Allah has given them over them.”
Ibn Maajah (1853) and al-Bayhaqi (14711) narrated that ‘Abdullah ibn Abi Awfa said: When Mu‘aadh ibn Jabal came from Syria, he prostrated to the Prophet (blessings and peace of Allah be upon him), who said, “What is this, O Mu‘aadh?” He said, I went to Syria and saw them prostrating to their archbishops and patriarchs, and I wanted to do that for you. The Messenger of Allah (blessings and peace of Allah be upon him) said, “Do not do that. If I were to command anyone to prostrate to anyone other than Allah, I would have commanded women to prostrate to their husbands. By the One in Whose hand is the soul of Muhammad, no woman can fulfil her duty towards Allah until she fulfils her duty towards her husband. If he asks her (for intimacy) even if she is on her camel saddle, she should not refuse.”
Prostration is for Allah alone, and even according to Hazrat Mohammad (P.B.U.H) it is not permissible to prostrate to anyone or anything other than Allah, either by way of greeting or by way of worship.