It is a moot point whether the husband of Shamima Begum, Yago Riedijk, a Dutch National, would be able to return to the Netherlands at any time in the near future and whether his wife could join him there.
The Netherlands does not have a policy of facilitating the return of Dutch nationals from Syria where they do not have a diplomatic mission. Riedijk is currently being held by a Kurdish group somewhere in northern Syria after the Daesh were defeated and lost their remaining stronghold to the Syrian government forces.
On the basis that Riedijk has only Dutch nationality (otherwise were he to have dual nationality of another country his Dutch nationality could be revoked , if it is proved he has committed offences so that to be a threat to the sovereignty of the Netherlands), he would have to make his way to the nearest Dutch Embassy in Iraq, Turkey or the Lebanon if there is to be any possibility of his return to the Netherlands. Since the Kurds are holding him, it is unlikely he will be released simply to make his journey to freedom. If he managed to get himself to the nearest Dutch Embassy, he will be returned to the Netherlands, and face the due process of the law.
Furthermore, Dutch law does not recognise a foreign marriage where one of the parties was under 18 years of age at the time when the marriage took place. Begum was a child at only 15.
In addition, the marriage was no doubt conducted under the Daesh interpretation of Islam, and since it is a proscribed organisation, it is unlikely that the authority that conducted the marriage would be recognised under Dutch law. Since Begum, his wife has been stripped of her British nationality, if she did manage to reach the Netherlands (her husband wants her to return with him), she may also face the due process of law there whilst her appeal against revocation of her British citizenship takes its course through the usual channels in the UK.
As regards the child of this union, he is an innocent pawn caught up in a situation not of his making. There is a huge risk of the child being taken into the care of the Dutch authorities and thereafter fostered out, as even if Begum was eventually able to join her husband in the Netherlands, it is unlikely she or her husband would be regarded as fit parents.
However the Netherlands faces a shortage in foster families, and it may take time for fostering to take place during which period the child will have an uncertain future in the care of the Dutch social services.
As a final point, if Begum managed to obtain Dutch nationality and the family wanted to return to Britain as EU citizens, she would as would her husband, under the UK immigration rules after Brexit, need to come to the UK prior to 31 December 2020 and apply for pre-settled status here, but it is unlikely they would be permitted to set foot on this island on account of being a threat to public safety and security.
Should you have any immigration and or nationality issues in the UK please contact Gulbenkian Andonian Solicitors for advice and assistance.