He is studying in the west; should he offer the udhiyah (sacrifice) there or appoint someone to do it on his behalf in his own country?

What is prescribed is for the sacrifice to be offered in
the place where the person offering the sacrifice is, as it is
prescribed for the person offering the sacrifice to slaughter the animal
himself and eat from it. The purpose of the sacrifice is not only to
obtain the meat; rather the purpose is to make manifest this symbol of
Islam. 

Shaykh Saalih al-Fawzaan (may Allah have mercy on him) said: 

The Prophet (blessings and peace of Allah be upon him) used
to slaughter the meat for the udhiyah and ‘aqeeqah in his house in Madinah
and he did not send any of that to Makkah, even though it is superior to
Madinah and there were poor people there who might have been in greater need
than the poor of Madinah. Yet it was limited to the place where Allah
prescribed the act of worship should be done. So he did not slaughter the
hadiy (sacrifice offered by the pilgrim during Hajj) in Madinah and he did
not send meat from the udhiyah and ‘aqeeqah to Makkah. Rather each type of
sacrifice was slaughtered in the place where it was prescribed for it to be
slaughtered. “The best of guidance is the guidance of Muhammad (blessings
and peace of Allah be upon him) and the worst of matters are those which are
newly invented, and every innovation is a going astray.”

End quote from al-Muntaqa min Fataawa al-Fawzaan
(50/10) 

This is the basic principle, that a person’s sacrifices
should be offered in the place where he himself is, and he should not
appoint someone to do it on his behalf in another country. But if the one
who wants to offer the sacrifice is in one country and his family are in
another country, if he is able to offer two sacrifices, one in the country
where he is and the other where his family are, then this is best. But if he
is not able to do that, then there is nothing wrong with him sending money
to his family so that they can offer the sacrifice on his behalf in their
country. 

Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) was
asked: 

The worker who comes to this country is far away from his own
land, and he has children there, and they are in greater need than those who
are here. Is it better for him to offer his sacrifice here, or to send
something to them so that they can offer the sacrifice on his behalf there?
You know how great their need is in some Muslim countries. 

He replied: 

What I think should be done in this case is to offer the
sacrifice here and there. If he cannot do that, then he should offer the
sacrifice there, so that his family can enjoy the meat of the sacrifice
during these blessed days.

End quote from al-Liqa’ ash-Shahri (1/440) 

He was also asked: 

We are not among the people of this land, and it is no secret
to you that our families are in great need of the sacrifice and to be able
to benefit from the meat and skin. Most of them are poor. Can we send the
price of the sacrifice to them, and appoint someone to do it on our behalf?
Please note that the purpose behind it is to practice the ritual openly. 

He replied:

If a person is in one country and his family are in another
country, there is nothing wrong with him appointing someone to offer the
sacrifice on his behalf where his family are, so as to bring joy to his
family and let them benefit from the meat, because if he offers the
sacrifice in the foreign country, then who will eat of its meat? Perhaps he
will not find anyone to whom he can give it in charity. Therefore we think
that if a person has a family elsewhere, he should send them the price of
the sacrifice, so that they can do the sacrifice there. 

End quote from al-Liqa’ ash-Shari (2/306) 

And Allah knows best.