You don't actually really need truth tables for VHDL. It's control code, so it's closer to programming in its own way. It might be easier if you start by mapping out the logic/control flow/decisions, use that to get the state diagram and get the truth table from the state diagram.
Start with the different elements/states:
ITEM NUMBER (00||01||10||11)
DISPENSING LED (0,1)
Separate names with a comma.