I would buy the "official study guide" from Hesi and use the one you bought from bookstore as a supplement.
Math: focus on fractions(addition,multiplying, dividing). Focus on addition and subtraction of decimals. Focus on proportions a lot!!. Focus in house hold measures( the one in the official study guide is perfect) literally everything was on it.
Vocabulary: it's kind of random but again I suggest you buying the Hesi book.
Grammar: basic grammar. A lot of "what's wrong or needs to be removed from sentence" questions.
Reading: normal comprehension.
That's all we had to take for ours. I still have my Hesi book. If u need it let me know I will be happy to send your way. Private message me your address. Hope I can help. I've been there before so I know how stressful it is.