A.) Take control of oneself. Wake up to a predicament. ‘Grip’ is used in the sense of taking control over your emotions and used when someone appears apprehensive, scared or timid.
“She was very scared about her first time driving on the freeway, but I told her to breathe deeply and get a grip if she plans to learn to drive.”
B.) Get a grip on suggests one is trying to understand a phenomena.
“The physics scientist was trying to get a grip on why black holes appear and disappear.”