The little girl in red dress cautiously danced a waltz Re adverb (s) and/or adveb pharse (s) in the sentence is/are in red dress only, cautiously only, both in a red dress and cautiously

The adverbs in the sentence is "cautiously only.

Explanation:

An adverb is that element that defines the meaning of verb in different way. In the sentence above the girl in red dress danced but cautiously i. e. cautiously defines the manner of her dance.

So it is an adverb. We can also check adverbs by questioning "where", "when", "how" etc. red dress is the noun that is worn by the girl, it doesn't have the meaning or sense of defining the noun of showing her manner so it is not an adverb.