vs
Ash Blossom & Joyous Spring
Card Text: When a card or effect is activated that includes any of these effects (Quick Effect): You can discard this card; negate that effect.
● Add a card from the Deck to the hand.
● Special Summon from the Deck.
● Send a card from the Deck to the GY.
You can only use this effect of “Ash Blossom & Joyous Spring” once per turn.
Red-Eyes Fusion
Card Text: Fusion Summon 1 Fusion Monster that lists a “Red-Eyes” monster as material from your Extra Deck, using monsters from your hand, Deck, or field as Fusion Materials, and if you do, its name becomes “Red-Eyes Black Dragon”. You cannot Normal or Special Summon other monsters the turn you activate this card. You can only activate 1 “Red-Eyes Fusion” per turn.
The Verdict
Case 1: Player-B activates Red-Eyes Fusion, Player-A responds with Ash Blossom: Red-Eyes Fusion is negated and destroyed.
WINNER = Ash Blossom
Further Resources
See Ash Blossom vs Red-Eyes Fusion discussion here.