She is a resident and has to file in whichever country she has a home available, closest ties, licenses, bank accounts, etc. There is a tax convention between the two countries which will determine whether she is considered a permanent resident for filing purposes. In Canada, you file a tax return if you are resident, usually more than 180 days. Normally, treaties say that if a home is only available in the one country (for example, only in Canada, no home available in the Phillipines), then you are considered a resident of that country for filing purposes. There are various tie breaker rules if you have a home and close ties to both countries.
The tax convention will also determine the tax treatment of employment income earned in a country where the individual is not considered a resident. For example, if the stay is temporary and they have a home in the Phillipines to go back to. It is really important that you look at the tax convention between the two countries.
Note that 99.9% of the countries in the world tax based on residency. Only the United States and one other country I can never remember the name of tax based on citizenship.
