off her guard vs napping

off her guard and napping both are adjectives.

Word	Noun	Adjective	Verb	Adverb
off her guard	No	Yes	No	No
napping	No	Yes	No	No

As adjectives, off her guard and napping are synonyms defined as:

Other synonyms of off her guard include off-guard, off guard, off his guard, off one's guard, off your guard.

off her guard (adjective)	napping (adjective)
not prepared or vigilant	not prepared or vigilant