Apple's returns policy only applies within the country of purchase.
Aside from the returns aspect, you should also consider the warranty implications. Generally, you should aim to purchase a device in the country within which you intend to spend most time - as this significantly simplifies the warranty and claims position should you ever need to call upon it.
If your Mom is considering such a generous gift, you might be best advised to persuade her to allow you to purchase the device yourself where you are. This addresses both the potential return/exchange requirement (note, this option is only available within 14-days of purchase) and the warranty. You should also note that the optional AppleCare+ insurance plan, should you require it, will only be honoured within the country of purchase.
A further consideration is shipping from overseas. The device will have to be shipped with an appropriate customs declaration; tax/import duty will likely be assessed and become payable when you receive it in your country.
Finally, you may have a better idea about any new product introductions on September 9th - as Apple has a "Special Event" at which the new range of iPhone and other devices are expected to be announced.