Of course, when a domestic helper has finished 12 months, she was entitle 7 days annual leave. She has the right to take the annual leave BUT you, her employer, also have the right to arrange the date for her. Its all up to both of you under discussion. If you do not want her take the annual leave on such period, you should explain your situation.
As I do not know your relationship with her, however the following be better follows based on my friends' experience
Although she is entitle to 7 day leave, pl ensure that (a) she will arrange for her own airticket and pay for it, no advance
(b) no advance salary paid even if she request
(c) ask her to sign a letter to the effect that she will terminate the contract by the date of return where you will keep it and submit it to the immigation if necessary(this is to save you trouble in case the maid runs away and does not report duty)
(d) check all her stuff and send her to the airport
(to avoid any stealing of your things)
it is maid's common problems of running away without notifying their employer, stealing things and heavy debts.
Beware of these and take care.