If you mean figurative language then
"air of night"
The correct answer to this open question is the following.
You forgot to include the options of the question, however, we can answer the following.
A correct analysis of the sentence would be "The prepositional phrase “on the park bench” acts as adjectival phrase."
In this case, the prepositional phrase is going to modify the non that is " the kindly old man." The preposition in the sentence is "on the bench," the place where the old man is seated while feeding the pigeons with breadcrumbs.
I think the sentence that uses it correctly is the last one.
Well I won't write the essay for you but here's what i'll do,
Frankenstein is a novel filled with prejudice. He hopes for friendship with the blind father because he knows that if the blind man could see he would be horrified and be scared of Frankenstein, which would lead to Frankenstein having no friends and being lonely. People judge Frankenstein on his looks, which then label him as a monster. It's the reason why he lashes out at times and is forever angry at everyone because they treat him like the monster he looks like, but not necessarily he acts like a monster. Frankenstein just wants to be treated normal, he wants to have friends and be happy with the way he looks. This theme is relevant to society today because people are often changing the way they look, or wishing they looked another way because people will judge them based on how they look. People self harm, lash out, similiar to what Frankenstein does, and they are treated differently because of how they look.
Something along the lines of that. You can expand the topics as how you see fit. Hope that helps you, comment if you need help with this more. :)