Is using same ground and VDD for MCU and motor driver module safe?
It's not wrong or dangerous, but you do have to be mindful of where the ground currents are flowing. Remember that your "ground" wire or PCB trace is not a superconductor, but rather a very small resistor. When you have 2A flowing through this, it can lead to a significant change in voltage (think of Ohm's law: voltage = current * resistance). If your motor controller is using PWM to control the motor speed, then there will be 2A in the ground trace one moment, then 0A the next, and this changing voltage drop can show up as noise to your MCU depending on where it and its voltage regulator are placed.

I answered a similar question recently with some more specific advice.