All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
In such matters, the customs should be taken into account, it is for this reason that the scholars said that a husband should allow his wife to visit her parents from time to time according to the customs.
Your wife is obliged to obey you in what you mentioned especially that you allowed her to visit her parents for the period which you mentioned in the question, and you are not obliged to give her permission to visit them for two or three days or a week, as she asked you.
However, as long as you can give her permission for the visit without you being harmed, then you should do so, because this brings more affection between the spouses and leads to having good relations with the in-laws.
Finally, a husband is permitted to put some restrictions on his wife by which he achieves a benefit without harming her whether it is in visiting her family or her other relatives.
For more benefit, please refer to Fatwa 82969.
Allaah Knows best.