Yes they are.
They are cousins: Beatrice's father was Leonato's brother.
Don Pedro and Don John are brothers. Leonato is Hero's father. Hero and Beatrice are cousins. Antonio and Leonato are brothers.
Beatrice is. And vice versa.
Much ado about nothing by William shakespeare
leonato father to hero and guardian\uncle to beatrice
Claudio and Hero; Beatrice and Benedick.
Beatrice was upset about the way Claudio acted during the wedding when he accused Hero for being with another man. He hurt Hero and to that Beatrice felt that Claudio needed to be killed.
Hero and Ursula have a conversation and make Beatrice think that they don't want her to hear it. In fact they do want her to hear it. The conversation says that Benedick has revealed his love for her to the others when in fact he has done nothing of the sort.
The play ends in marriages (Claudio and Hero, Beatrice and Benedick) not funerals. Nobody dies in the play.
Claudio marries Hero. Benedick marries Beatrice. Don John is captured and will be punished for his crimes. All is well.
hero is not the hero in much ado about nothing, that's just her name!
If you take out the Claudio and Hero romance, yes. Restoration adaptations of the play which focus on the Beatrice/ Benedick relationship had this title, as does the opera based on the play.