What is the name of a long speech made by a character that other characters hear called?
a. an aside
b. a dialogue
c. a monologue
d. a soliloquy

The answer is letter c.   A monologue is a kind of speech which is delivered by one person . It is a long one-sided conversation.  On this dramatic device, only one person does the talking.  

An aside is a device used in drama wherein a character speaks to the audience and the audience, in convention, is to realize that the speech of the character is unheard by the other characters on stage.
A dialogue on the other hand is a spoken or written exchange of conversation between two or more people.
Soliloquy comes from the Latin words “solo” and “loquor”  which means “to oneself “ and “ I talk”, respectively. It is a device commonly used in drama whereby the character speaks to himself or herself, conveying thoughts and feelings, thereby sharing them with the audience.

The meaning of the phrase "thou art wedded to calamity” is same as the sentence: your marriage will be a complete disaster.the message conveyed in the sentence is about marriage as the word "wedded" connotes, and the term "calamity" refers to disaster.