Does Moon Bard's Lunary Vitality apply to all targets of Mass Healing Word/Mass Cure Wounds?

I tried looking around for an answer on this, but haven't found anything yet. If it does, I feel like it would make this slightly underwhelming feature significantly better.

Lunar Vitality. Once per turn when you restore Hit Points to a creature with a spell, you can expend a Bardic Inspiration die and increase the amount of Hit Points restored by a number equal to a roll of the Bardic Inspiration die. The creature's Speed also increases by 10 feet until the end of its next turn.

I think there's two ways to read this:

Option 1) Once per turn when you restore Hit Points to a creature with a spell, you can expend a Bardic Inspiration die and increase the amount of Hit Points restored to that creature by a number equal to a roll of the Bardic Inspiration die.

Option 2) Once per turn when you restore Hit Points to a creature with a spell, you can expend a Bardic Inspiration die and increase the amount of Hit Points restored by that spell by a number equal to a roll of the Bardic Inspiration die.

I'd love some clarity on which reading is correct or if this is open to DM interpretation.