There are no “trap” talents on Morales. All her talents have an above 50% win rate. There might be worse talents for players that don’t understand her kit, but that player would likely struggle with Morales regardless of what talent they chose.
If you mean quest talents, I almost always go grenade whether I’m in ranked, ARAM, or QM. It’s especially easy to complete in ARAM and synergize with other talents more quickly because of more opportunities for grenade to hit more enemies. Grenades also generate energy.