Bob Ewell resents Judge Tayor (and Atticus) for simply doing the job to investigate the case. Of course, what he's really afraid of is getting found out for having beaten up his own daughter, then blaming Tom Robinson for it.
He also bears a grudge against Link Deas, who has hired Tom Robinson's wife Helen to work for him. Link protects Helen and warns Ewell to not give her any more trouble, or he will find himself arrested on harassment charges.
Bob Ewell bears a grudge because nobody in Maycomb truly believed him and Atticus made him look like a fool on the stand, contradicting him and Mayella.
Ewell sees the judge, the sheriff, and Atticus as his enemies.
Bob hates Atticus and the judge because they are taking the side of justice. Atticus is a strong lawyer and is doing anything and everything in his power to save the innocent Tom Robinson that was framed because of his evil deeds. He also hates Link Deas because he protects Tom's wife, and he wants to get revenge on them.
Bob Ewell holds a grudge againts Atticus because he made him and Mayella looks like fools on the stand, Atticus did his job really well to find out the complete truth from Bob and Mayella by Manipulating them. He sees Atticus, Judge Taylor and the children as enemies for making him look like a bad person at court.
Bob bears a grudge on Atticus because he was Tom's lawyer. He also bears a grudge on Link Deas, who hired Tom Robinson's wife Helen to work for him.