Since your parents is staying with your, I think it is perfectly alright to hire a maid. Your parents will be at home most of the time right? If so, they can help to supervise the maid. Or you can plan this way: your parents help to tc of your baby while the maid take cares of the housework including washing baby's stuff. And with your parents around I'm sure your will feel more assured that the maid cannot get any chances to do anything to your baby and if she is not good, your parents will spot it immediately. But if your parents will not be staying with you for long term then I think hiring a maid might not be the best option since you and your wife gonna wk.
As for your wife, I think it is pretty normal for her to feel stress and fearful. The 1st 3 mths of parenthoos is never easy, esp for a 1st time mother. All she needs now is the whole family's understanding. Try to help her as much as you can. I rmb I used to cry alot when dear son was young, even quarrelled with my hub cos I felt that he wasnt doing much (though he has done alot). Dont wry, this is just a passing phase. =)