What is the ruling on a husband and wife eating with friends (a man and his wife) at the same table in Europe, given the wife's commitment to hijab and religious matters?

It is not permissible for men and women to eat at the same table if it leads to fitnah (temptation/strife). However, it is permissible if fitnah is absent, provided that Islamic guidelines are adhered to. If the wife is veiled and committed, there is no harm in her eating at a table where a non-mahram man is present. Similarly, if the husband does not fear fitnah from his wife sharing a table with his friend's wife [or from him sharing a table with his friend's wife]. Nevertheless, it is safer to avoid this.