Fragile - tenuous: Whatever they were in the mountains, they could be no more. However tenuous their well-being, however much they had suffered and would suffer again, they had found a way out of the wilderness.
Tenuous means fragile or delicate. After the people found their way out of the wilderness, they were most likely fragile from a lack of proper care and nutrition.
Lobby - beg and barter: In order to consummate the ancient sacrifice—to impale the head of a buffalo bull upon the medicine tree—a delegation of old men journeyed into Texas, there to beg and barter for an animal from the Goodnight herd.
The verb lobby means to persuade. In this passage the old men are trying to persuade someone for an animal.
Pensive - brooding: My grandmother was spared the humiliation of those high gray walls by eight or ten years, but she must have known from birth the affliction of defeat, the dark brooding of old warriors.
Pensive means to be deep in thought. Brooding also means to be deep in thought but usually over something that has a negative outcome. The person brooding usually wishes to change what has happened.
Antagonist - Enmities: Some of them painted their faces and carried the scars of old and cherished enmities.
Enmities is another word for something that is hated, just like an enemy. An antagonist goes against a person or thing and is often hated or strongly disliked so this would be the best choice.
The mood and atmosphere to the trial is really built up over many chapters. Before the trial every begins we see the bigotry of the town as well as the humanity in a small handful of characters. So, when the trail finally takes place the mood and atmosphere is tense with a touch of somber resignation. I say this because deep down the reader, like Atticus, knows that the trial will not go well. The jury is made up of a bunch of older white men who cannot see past their set ways. The court is full of people, “We knew there was a crowd, but we had not bargained for the multitudes in the first floor hallway”. The blacks and the whites are segregated and Scout and Jem get to sit in the black section. Lee sets the symbolism and the tone for the trial perfectly.
Your husband/wife's mother
Science fiction – a genre of fiction dealing with the impact of imagined innovations in science or technology, often in a futuristic setting. or depicting space exploration. Exploring the consequences of such innovations is the traditional purpose of science fiction, making it a "literature of ideas".