Start by casting Paralysis. It almost always works against Mondo Mole. Fire works better on it than Freeze. Mondo Mole can put up a psychic shield, so stick to physical attacks while it is in effect.

You might need to just let Paula die because of how weak she is likely to be if you fight Mondo Mole right after rescuing Paula.

Once Mondo Mole is gone, you can go to Lilliput Steps. If you went here after defeating Mr. Carpainter, go on to the section about going back to Twoson with Paula.