Bonus??
My company only gives me bonus if I contributed to the revenue growth. Did your helper contributed to the increment in your household income?
By the way, from what you have listed, I don't see the reason you have to even think about giving bonus. She may not be the worse compare to those mentioned in BK, she for sure is one of those "bad helpers". Yell at the son but good to the daughter?! What kind of helper she is?