All perfect praise be to Allah the Lord of the Worlds. May His peace and blessings be upon Prophet Mohammad and upon all his family and companions.
According to the general rule, a mother is most entitled to the custody of her children as long as she is fit for that and there is no hindrance preventing her from that, such as marrying another man or a non-mahram relative of her children.
This is supported by the following narration: " 'Amr b. Shu'aib on his father's authority said that his grandfather (Abdullah ibn Amr ibn al-'As) reported: A woman said: "Messenger of Allah, my womb is a vessel to this son of mine, my breasts, a water-skin for him, and my lap a guard for him, yet his father has divorced me, and wants to take him away from me. The Messenger of Allah (PBUH) said: You have more right to him as long as you do not marry." {Abu Dawoud}.
Mother`s place of residence is considerable in the event she took custody of her children as long as she lives within the boundaries of the Hashemite Kingdom of Jordan. She is allowed to move them to her place of residence so long as that is in her and their best interest. In addition, it isn`t allowed for anyone to move them to another place except with her approval and provided that it lies in the best interest of the children in her custody. This is the view adopted in Article No.(175) of the Jordanian Personal Status Law. It reads: "Guardian or custodial mother`s travel with the child under their custody doesn`t affect their right to keep that child as long as the travel doesn`t affect the child`s best interest. However, if it was established that the travel affects the interest of the child then it should be banned and the right to custody is temporarily transferred to the next person entitled to that."
Moreover, Article No.(184) of this Law reads: "A-Subject to the provisions of custody of child, the guardian has the right to oversee the affairs of the child, take care of him/her and select the type and place of receiving his/her education and that is in the custodial mother`s place of residence. Moreover, it isn`t allowed to move the child from her place of residence save with her approval or for a necessity that achieves the interest of the child."
In conclusion, determining the location of the house bought by the guardian as a gift to the children depends on the instructions of the donor. If there aren`t certain instructions then what counts, here, is the best interest of the children in this regard. If it is more beneficial to purchase a house for them in the area where their father`s family and clan lives then this should be done as such along with preserving the right of the mother in keeping her children in her place of residence. Moreover, the house could be rented and the rent paid to the children.
However, if it is more beneficial to buy them a house somewhere else then it should be done as such, whether in the area of their clan or another governorate; however, in case of conflict between the mother and children`s grandfather, the Sharia judge alone has the final say in this regard. And Allah the Almighty knows best.