Is it o.k. if her husband takes her to the airport and her brother meets her in her country?
Question

                My wife, children and I live in France for certain reasons. I cannot visit my family in my home country this summer. But my wife insists on going alone with our children, one is 3 years old and the other is one year and half. Although she knows it is not permissible, she justifies this by the importance of keeping womb relations.

1- Is it permissible to take her to the airport, and in her country her brother will collect her?

2- What shall I do if she insists on going? I can stop her even though this will cause a problem between us.
Praise be to Allah.It is not permissible for a 
    woman to travel without a mahram, whether the journey is for an act of 
    worship such as Hajj or visiting and honouring her parents, or it is a 
    permissible journey such as a vacation and the like. The evidence for that 
    is as follows: 
1 – The Prophet  (peace 
    and blessings of Allaah be upon him) said: “No woman should travel except 
    with a mahram, and no man should enter upon a woman unless her mahram is 
    with her.” A man said, O Messenger of Allaah, I want to go out with 
    such-and-such an army and my wife wants to go to Hajj. He said, “Go (to 
    Hajj) with her.” Narrated by al-Bukhaari (1862). 
Muslim (1339) narrated from 
    Abu Hurayrah that the Prophet  (peace and blessings of Allaah be upon 
    him) said: “It is not permissible for a woman who believes in Allaah and the 
    Last Day to travel the distance of one day, except with a mahram.” 
And there are many 
    ahaadeeth which forbid a woman to travel without a mahram; they are general 
    in meaning and apply to all kinds of travel. 
2 – Travel may be 
    exhausting and difficult, and because of her weakness a woman needs someone 
    to help her and stand by her. Something may happen that makes her lose her 
    mind and behave contrary to her nature if she has no mahram with her. This 
    is something that is often seen nowadays because there are so many accidents 
    with cars and other means of transportation. 
Moreover, travelling alone 
    may expose her to temptation and evil, especially as there is a great deal 
    of corruption. There may be people sitting near her who do not fear Allaah, 
    and they may try to tempt her to do haraam things. So it is only wise that 
    she should be accompanied by a mahram when travelling, because the purpose 
    of having a mahram with her is to protect her and look after her. Travel is 
    a situation in which unexpected things are expected to happen regardless of 
    the amount of time the journey may take.  
Al-Nawawi (may Allaah have 
    mercy on him) said: The point is that everything that is called travel is 
    forbidden for a woman without a husband or mahram. End quote. 
More than one of the 
    scholars narrated that the fuqaha’ were unanimously agreed that a woman is 
    not allowed to travel without a mahram, except in exceptional cases. 
Al-Haafiz Ibn Hajar (may 
    Allaah have mercy on him) said: al-Baghawi said: They did not differ 
    concerning the fact that a woman may not travel for anything but the 
    obligatory Hajj except with a husband or mahram, except a kaafir woman who 
    becomes Muslim in daar al-harb or a female captive who escapes. Others 
    added: or a woman who becomes separated from her group and is found by a 
    trustworthy man, in which case it is permissible for him to accompany her 
    until he brings her back to her group. End quote from Fath 
    al-Baari (4/76). 
The scholars differed as to 
    whether it is permissible for a woman to travel for the obligatory Hajj 
    without a mahram. The correct scholarly view is that it is not permissible. 
    This has been explained in the answer to question no. 
    34380. 
What you have mentioned 
    about taking the wife to the airport and her brother meeting her in the 
    other country is not acceptable, rather the husband or a mahram must 
    accompany her throughout the journey. 
The wife has to obey her 
    husband, especially if he tells her to do that which constitutes obedience 
    to Allaah and he forbids her to do that which constitutes disobedience to 
    Allaah. 
You have to explain the 
    shar’i ruling to her, and tell her that the believer has no choice when it 
    comes to the ruling of Allaah or His Messenger. 
Allaah says (interpretation 
    of the meaning): 
“It is not for a 
    believer, man or woman, when Allaah and His Messenger have decreed a matter 
    that they should have any option in their decision. And whoever disobeys 
    Allaah and His Messenger, he has indeed strayed into a plain error”
[al-Ahzaab 33:36] 
“The only saying of the 
    faithful believers, when they are called to Allaah (His Words, the Qur’aan) 
    and His Messenger (صلى الله عليه وسلم), 
    to judge between them, is that they say: ‘We hear and we obey.’ And such are 
    the successful (who will live forever in Paradise)”
[al-Noor 24:51]
That should be done in a 
    kind and gentle manner, not a harsh and cruel manner. 
We ask Allaah to guide you 
    both. 
And Allaah knows best.