What is the meaning of the idiom "writing on the wall"?

a.
messages left for people one knows

b.
a sign that something bad is about to happen

c.
children's drawings and scribbling

d.
a warning of danger to keep people away

Iam awful at english and am so confused sos ignore the completely wrong diagram above

Read this excerpt from "ain't i a woman? " by sojoumer truth in which three sentences does she make an emotional appeal to the audience by talking about her personal hardships? well, children, where there is so much racket there must be something out of kilter. {i think that 'twixt the negroes of the south and the women at the north, all talking about rights, the white men will be in a fix pretty soon.} but what's all this here talking about? {that man over there says that women need to be into carriages, and lifted over ditches, and to have the best place everywhere. nobody ever me into carriages, or over mud puddles, or gives me any best place} and ain't i a woman? look at me! look at my arm! {i have ploughed and planted, and gathered into bars, and no man could head me! } and ain't i a woman? i could work as much and eat as much as a man - when i could get it - and bear the lash as well! and ain't i a woman? {i have borne thirteen children, and seen most all sold off to slavery, and when i cried out with my mother's grief, none but jesus heard me! } and ain't i a woman? {then they talk about this thing in the head, what's this they call it? [member of audience whispers, "intellect") that's it, honey.} what's that got to do with women's rights or negroes' rights? if my cup won't hold but a pint, and yours holds a quart, wouldn't you be mean not to let me have my little half measure full?

Based on part two of trifles, which of the following images most reinforces the them of loneliness that exists throughout the play?