The correct Active/Passive form of the given sentence is:

☀ The mistake could not have been made by them.

Explanation for other options:

☀ The mistake can not have been made by them. This option is in the passive voice, but it uses "can not have been made" instead of "could not have been made." Both forms are grammatically correct, but the original sentence uses "could not have made," so the correct form should be "The mistake could not have been made by them."

☀ The mistake should not had been made by them. This option is in the passive voice, but it uses "should not had been made" instead of "could not have been made." The original sentence uses "could not have made," so the correct form should be "The mistake could not have been made by them."

☀ The mistake will not has been made by them. This option is not grammatically correct. The correct form should be "The mistake could not have been made by them."