What are some signs of menopause?

My grandpa (my dad's father) ped away on Monday, since then my mother (who has been saying and doing crazy things for about the last year) flipped out on us. She screamed at my dad, his oldest sister, and their step mom. Then when I told her to 'stop it and calm down for a minute' she yelled at me. After that she stormed out of my grandpa's house and left for like two hours. Could this be menopause or should I be worried about a more serious problem?