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 is forbidden to sit at a table where alcohol is being served. It is also forbidden to accept any invitation or attend any party where these sins (drinking alcohol) are committed regardless of the person who is inviting you, whether he is a relative, a friend, or otherwise.
Jabir narrated that the Prophet said: “Whoever believes in Allah and The Last Day should not sit at a table where alcohol is served.” [Ahmad]
It is unlawful to obey or be lenient to any person whomsoever he is in doing what Allah has forbidden. The Prophet said: “There is no obedience in disobeying Allah; obedience is required only in what is permissible.” [Al Bukhari and Muslim]
Allah Says regarding how to keep company to non-Muslim parents (what means): {But if they endeavor to make you associate with Me that of which you have no knowledge, do not obey them but accompany them in [this] world with appropriate kindness...} [Quran 31:15]
We advise you not to befriend any non-Muslim. Your friends should all be people who help you in doing good and righteousness and avoiding bad and evil; these are found only among Muslims.
Your wife is right in refusing to accompany such people or go out with them on their picnics or trips as this means sitting with them and socializing with them while they are committing sins and while she can not prevent them from doing so.
Know also that the Muslim should be proud of his religion and his personality should be distinguished by Islamic characteristics everywhere and all the time. The Muslim should observe the Islamic rites whenever possible. Indeed, Islam is the true religion of Allah, The Owner of this world. So, whoever becomes a Muslim should be proud of it because he worships The Lord of lords, The Creator of the World, The Master of All, The One Who can never be defeated, The One Whose Rule is Final, The Almighty, The Great.
On the other hand, know that it is from your parent's rights and the right of any non-Muslim you know that you tell them about this great religion, and you call them to become Muslims. Let them know that whoever does not enter this religion, he will become a loser on The Last Day and will be thrown into Hellfire, and whoever accepts this religion, he will have much goodness on the Last Day. If they refuse, you will have done what is required and you will not be held responsible for their fate before Allah on The Day of Judgment.
For more benefit on the limits of obedience to parents, please refer to Fatawa 271255, 131695, 123554 and 401131.
For more benefit on correct approach to give advice to parents or elderly people, please refer to Fatawa 297928, 343564, 351385 and 13288.
Allah knows best.