I'll assume you are a novice lifter (since you're doing stronglifts), with a goal of strength.
You don't need additional tricep work. Triceps are worked every workout with either bench press or overhead press.
If you have the capacity for extra arm work at the end of a workout that included benching or pressing 5x5, you must be just beginning stronglifts. Soon, you'll have workouts where you'll only be able to barely complete the prescribed number of reps. That is sufficient to stimulate a strength increase for the next workout. There is no need for additional work beyond that.
If you begin stalling on the bench or overhead press, the suggested accessory exercises are chin-ups and pull-ups, but these are part of the optional program anyway. Much later on, intermediate lifters may include dips or lying tricep extension. They didn't become intermediate lifters because they do these exercises; they're doing these exercises because they're intermediate lifters.
For bicep work, Stronglifts includes rows, and optional chin-ups and pull-ups. These will make your biceps stronger. I can't think of an activity that requires isolated, open chain biceps contraction, so there is no need to train that movement.
For ab work, you don't need any accessory exercise. Your abs will get stronger in proportion to your need for them as you progress on your main lifts. Once you're well past the novice stage, you may need some accessory ab work, but not now.
If you follow Stronglifts, you will not get t-rex arms, and your abs will become as strong as they need to be.