Answer: Option C
The sentence "My sister along with her two children has arrived" is grammatically correct. The subject of the sentence is "My sister along with her two children," which is a collective noun that refers to a group of people. In this case, the subject is singular because it refers to a single group of people. Therefore, the verb "has" should be used instead of "have".
Here is an explanation of the possible options:

• Option A - is: This verb is singular and is used to describe a single subject. It is not appropriate for the sentence because the subject is a group of people.
• Option B - are: This verb is plural and is used to describe multiple subjects. While the sentence refers to multiple people, the subject is considered singular because it refers to a single group of people.
• Option C - has: This verb is singular and is appropriate for the sentence because it agrees with the subject of the sentence, which is considered singular.
• Option D - have: This verb is plural and is not appropriate for the sentence because the subject is considered singular.
• Option E - None of these: This option is incorrect as Option C - has is the correct answer.

In summary, the correct verb to use in the sentence "My sister along with her two children has arrived" is "has". The subject of the sentence is a collective noun that refers to a single group of people, so a singular verb should be used. Therefore, Option C - has is the correct answer.