The correct answer is: Neither your parents nor I were very glad of the fact that you failed your Math exam.
The verb “to be” is used in the past tense because the sentence is about a past event. The subject of the sentence is “neither your parents nor I”, which is a plural subject. The plural form of the verb “to be” is “were”.
The other options are incorrect because they are not in the past tense. The verb “has been” is in the present perfect tense, and the verb “have been” is in the past perfect tense. The verb “was” is in the singular form, which is incorrect because the subject of the sentence is plural.
The sentence “Neither your parents nor I were very glad of the fact that you failed your Math exam” means that neither your parents nor you were happy about the fact that you failed your Math exam.