You're referring to the episode 500 Keys from season 22, where Lisa says:
Get thee behind me, Namuche! That's the Buddhist Satan.
Namuci (sometimes transliterated as Namuche) does seem to be another name for Mara. From Wiki:
In the Maha Samaya Sutta, the defeated antagonist of the Buddha, Mara also known as Namuci or the "Dark One" is described as a corrupted Asura whose army consisted of "Sensual passions, Discontent, Hunger and Thirst, Craving, Sloth and Drowsiness, Terror, Uncertainty, Hypocrisy and Stubbornness, Gains, Offerings, Fame and Status wrongly gained, and whoever would praise self and disparage others"
This is verified by many other sources. From the online Chinese Buddhism Encyclopedia:
Mara: In theistic religions the Devil, sometimes also known as Satan or Beelzebub, is a being completely opposed to God and to goodness. [...] Mara is sometimes also called Kaõha, the Dark One (Majjhima Nikaya 1. 377), or Namuci (Digha Nikaya 2. 259).