Pronoun : -  any of a small set of words (such as I, she, he, you, it, we, or they) in a language that are used as substitutes for nouns or noun phrases and whose referents are named or understood in the context’ .

Indefinite Pronoun: are words that refer to persons or things in general and not to anything specific.

A pronoun that refers to person or thing in a general way (not in a definite way) is called indefinite pronoun. The indefinite pronouns everybody, anybody, somebody, all  each, every, some, none, one do not act for specific nouns, but function themselves as nouns.

Indefinite pronouns may be used without antecedents.

Example : - Are there enough seats for everybody ? Here , everybody is an indefinite pronoun as it is used to refer to people which is not specific or define .

In the question : -

1. Has everyone completed the work that was assigned for today? In this sentence , everyone is an indefinite pronoun as it is used to refer to people which is not specific .

2. I don't have anything smart enough. In this sentence , anything is an indefinite pronoun as it is used to refer to thing which is not specific .

3. Somebody has left his or her coat behind. In this sentence , somebody is an indefinite pronoun as it is used to refer to people which is not specific .

Thus , the Correct option is C , which is everyone , anything , somebody .

Pronoun : - A pronoun is a word that you use to refer to someone or something when you do not need to use a noun, often because the person or thing has been mentioned earlier. Examples are 'it', 'she', 'something', and 'myself'.

Indefinite Pronoun: are words that refer to persons or things in general and not to anything specific.

A pronoun that refers to person or thing in a general way (not in a definite way) is called indefinite pronoun. The indefinite pronouns everybody, anybody, somebody, all  each, every, some, none, one do not act for specific nouns, but function themselves as nouns.

Indefinite pronouns may be used without antecedents .

Example : - Did you meet anybody interesting at the party ? Here , anybody is an indefinite pronoun as it is used to tell about people that are not define .

In the question : -

1. I thought I heard someone call my name. Is anyone there ? in this sentence , someone and anybody are the indefinite pronoun . Someone is used to show about one people which is not definite . Anybody is used to show about people which is not definite .

2. I need something to wear to Jane's wedding. In this sentence , something is an indefinite pronoun as it is used to show about things which are not specific or definite .

Thus , the Correct Option is C , which is someone , something .

Pronoun : - Pronouns are words that take the place of nouns. We often use them to avoid repeating the nouns that they refer to .A pronoun is a word that is used instead of a noun or noun phrase. Pronouns refer to either a noun that has already been mentioned or to a noun that does not need to be named specifically.

Indefinite Pronoun: are words that refer to persons or things in general and not to anything specific.

A pronoun that refers to person or thing in a general way (not in a definite way) is called indefinite pronoun. The indefinite pronouns everybody, anybody, somebody, all  each, every, some, none, one do not act for specific nouns, but function themselves as nouns.

Indefinite pronouns may be used without antecedents.

Example : - One cannot get everything one desires. Here , everything is an indefinite pronoun as it is used to specify about the things which are not definite .

In the question : -

I searched all over, but couldn't find my notes ______________.

 In this sentence , anywhere is the correct indefinite pronoun as it  is used to specify about the place which is not definite .

Thus , the Correct  Option is C , which is Anywhere.