As the permanent last existed on the battlefield, it had a +1/+1 counter on it, so undying will not trigger. Yawgmoth the Undying cEDH Yawgmoth the Ineffable, the Father of Machines, the Lord of the Wastes, the God of Phyrexia is here. If that permanent had a +1/+1 counter on it, then receives enough -1/-1 counters for it to be put into a graveyard due to having 0 toughness or lethal damage marked on it, it won't return to the battlefield despite the state-based action of +1/+1 counters and -1/-1 counters 'cancelling each other out'. Undying relies on the last known information about the permanent just before it was put into a graveyard.However, like all tokens, it can't return to the battlefield and will cease to exist as a state-based action before the ability would go on the stack. Tokens can gain undying, and the ability will trigger if a token is put into a graveyard.An object returned to the battlefield with the undying ability is a new object with no memory of its previous existence.Multiple instances of undying trigger separately, but are effectively redundant as only the first instance to resolve will have any effect.Likewise, if a noncreature permanent becomes a creature, gains undying, and is put into a graveyard, the undying ability will still trigger even though that permanent won't be a creature when it returns to the battlefield.If a creature with undying stops being a creature, undying will still trigger. All cards printed with undying are creatures.

“Undying” means “When this permanent is put into a graveyard from the battlefield, if it had no +1/+1 counters on it, return it to the battlefield under its owner’s control with a +1/+1 counter on it.” 702.93a Undying is a triggered ability.From the Comprehensive Rules (June 16, 2023- The Lord of the Rings: Tales of Middle-earth)

Mtg undying