In British English, #1 is correct if you are at the clinic, your wife is at home and you want her to drive your son to the clinic.
#2 is correct if you all three of you are at home and you want your wife to drive your son to the clinic.
Speakers of American English will answer for themselves when they get up in a few hours' time.
In the meantime, click here, scroll down to the sixth entry and read earlier threads on this topic.
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