Here are a few templates to give you an idea of what a "Letter of Consent" should contain.
US only requires an adult witness, but you should get it witnessed by a Notary Public as some countries may require this.
(This is not
a US government website)https://travel.gc.ca.../consent-letter
(Canadian Immigration, a government website)
These are "fill it out online and print or save it" optionshttps://www.lawdepot...US#.W6r_suXPzAQhttps://sample-paren...d.pdffiller.comhttps://eforms.com/c...r-child-travel/https://www.rocketla...nsent-form.rl#/https://legaltemplat...travel-consent/
Canada also requests a copy of the child's Birth Certificate and a photocopy of the signature page of the passport of the absent parent who signed the "Consent to Travel" letter or a photocopy of the absent parent's national ID (drivers license/State ID if from US)
These may not be required, but are something that you should be able to present on request.
Specific to your situation.Entry requirements
for a Minor Child entering Philippines (unaccompanied by parent)
When the child is of Philippine ancestry, a Letter of Consent to Travel and proof of Philippine ancestry are required (If the child is using a non-Philippine passport, Mom's passport and child's birth certificate are sufficient for proof of ancestry)
MINOR CHILDREN WITH PHILIPPINE ANCESTRY
Minor children (unmarried and below 15 years old) with Philippine ancestry, who will travel to the Philippines accompanied by a Philippine grandfather, grandmother, guardian or relative, are exempt from waivers of exclusion and waiver of exclusion service fees. Thus, they do not need to apply for WEG at the port of entry. However, the accompanying travel companions of these minor children with Philippine ancestry are required to submit proof of the childrens Philippine ancestry to the Bureau of Immigration at the port of entry.
The mother or father of these minor children is also advised to execute an Affidavit of Consent to Travel, for submission to the Bureau of Immigration. The affidavit should state the name of the childrens travel companion and the latters relations with the children. The Affidavit has to be executed at the Philippine Consulate General.
The Philippine Consulate in New York version of the Affidavit of Support and Consent
The Philippine Consulate in Los Angeles version of the Affidavit of Consent, Support, Guaranty and Authorization
(The LA PDF is a 'fillable form'. Just type in any of the shaded fields and you can then print the filled out form)
Philippines does require these forms to be notarized.
Note that the text of these forms covers multiple situations. Delete the text that does not apply to you when copying the form into a word processor.
She should have the documents available at every border crossing, both exit and entry. They may also be requested by ticket counters, boarding gates and other points where travel documents are checked.
The adventures continue