I'm living alone for one month in Canada preparing for my Ph.D. and I'm waiting for my husband and my children to come within 2 months. What is the opinion of the religion of being alone?

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

Sister inquirer! You have committed two errors:
1) Travelling for more than 85 km without a Mahram (unmarriageable man). The Prophet (Sallallahu Alaihi wa Sallam) said: "It is Haram for a woman who believes in Allah and the last Day to go on a journey lasting for a day and night without accompanying a Mahram" [ Bukhari and Muslim ]
2) Residence in non-Muslim countries, which is originally Haram. But, if your studying/preparation for PhD is not available at some Muslim country and Muslims are in need of this specialization, then there is no objection to reside in non-Muslim country with the intention of return when you finish your study. More will be found on this subject in our Fatwa No. 81642.
As for residence alone, it is generally permitted provided that you live safely. Furthermore, it is better and safer to live with Muslim female students if possible. If there is some danger due to being alone, you are to hasten to return to your homeland and then you may go back to continue your study with your husband and children.
Allah knows best.