Structure of Question Tag in Future Tense with will is as follows :
Contraction of will not is won’t.
Hence, won’t you is the right usage.

Correct Option: C

Structure of Question Tag in Future Tense with will is as follows :
Contraction of will not is won’t.
Hence, won’t you is the right usage.

Here, money is an uncountable Noun. Hence,Singular Verb i.e. was spent is the right usage

Correct Option: B

Here, money is an uncountable Noun. Hence,Singular Verb i.e. was spent is the right usage

Rustam and I is the Sub. of the sentence, so the Nominative Pro. is used for the sentence for making it grammatically correct. Hence, I saw is the right usage.

Correct Option: B

Rustam and I is the Sub. of the sentence, so the Nominative Pro. is used for the sentence for making it grammatically correct. Hence, I saw is the right usage.

No error.

Correct Option: D

No error.

It is a past event. Hence, Past Simple i.e. I saw is the right usage

Correct Option: A

It is a past event. Hence, Past Simple i.e. I saw is the right usage