In literature, personification refers to non-human things such as objects, ideas, or animals that manifest human attributes. These things, though they are not human, somehow act like human beings. This literary device allows poets to give deeper meanings to their works by helping readers see things from a human perspective and connect to them with their emotions.
With this definition in mind, we can analyze the examples from the poetry of Emily Dickinson in your question. We'll start with an obvious personification: "The Nerves sit ceremonious, like Tombs." Nerves are bundles of fibers in a body's nervous system that convey messages by means of electrochemical impulses. However, in this line Dickinson gives nerves the human-like ability to sit. Not only can they sit, but they sit all lined up in a ceremonious manner like tombs.
Another clear personification is in the following lines in the same poem, which read,
The stiff Heart questions, 'was it He that bore,'
And 'Yesterday, or Centuries before'?
In this instance, the heart, which is an organ in the body, is given the human-like attribute of being able to question something. Dickinson even puts the question within quotation marks, suggesting that the heart also has the ability to speak out loud.
The next example in your question also includes personification: "Heart, we will forget him!" This is the opening line of a different poem in which Dickinson directly addresses her heart as if it is a living person, urging the heart (in this case representing the seat of the emotions) to forget a man that seems to have been important to her.
The correct answer to your question is the first option: "After great pain, a formal feeling comes." This line does not include personification because there is no attribution of human qualities to something that is not human.