"would have" is correct. "would" is commonly used for 'future in the past' to indicate that something will happen. The child was very excited all daybecause she knew that that night Santa would come. "she would have" is equivalent to "Santa would come".
It seems that none of the three options is correct. You cannot use "would have", either, because this verb tense [future in the past] is used in conditional sentences, [type II] , in reported speech as a past equivalent of the simple future tense , in past routines, and after the verb "wish".
Future in the past is only used in conditional sentences?? Where did you get this from??
Actually, you contradict yourself. You wrote that, "Future in the past is used...as a past equivalent of the simple future tense." Doesn't this apply to Daiana's sentence, too?
As far as I know, future in the past is used to express the idea that in the past you thought something would happen in the future.
I didn`t say that "would" is ONLY[?!] used in conditional sentences. Have I used the word only ? Where did you get it from?? I tried to explain that "would" can be used:
a] in conditional sentences type II:
If I were you, I wouldn`t go there.
b] habit in the past :
e.g. She would always send me strange birthday gifts.
She would ride the bike [=used to ride the bike] when she was very young.
c] reported speech [and as a past equivalent of the simple future tense]:
"I will visit them soon," said the doctor.
The doctor said he would visit them soon.
d] after wish:
I wish you wouldn`t make that noise anymore.
d] other uses:
e.g. I would be very grateful if you would send me the details [polite request]
Tim, I`d like to introduce you to my friend Deborah.[polite form of "want"]
I am sure I did not contradict myself. You misunderstood my point, or, maybe I did not clearly made myself understood.