Is Tasha street savy? Does she have experience of being on the street? If so, does she have any street friends?
Has she contacted the Public Guardian since leaving the group home? Where do you feel that she would go to get money?
(I am thinking of a welfare office)
Did she at one time know of an elderly fatherly type of person in the her past to whom she may have contacted? (other than her own Dad?) - perhaps a neighbour?
Have you checked youth shelters, homeless shelters, and mental health drop in clinics?
These questions may seem strange, but when one thinks about it, she would have to contact someone in this world.
No one can truly survive on their own without receiving some human contact, and in her case with her mental illness, she would certainly need medications supplied from somewhere. I am not familiar with the Ontario system re: those who live "independently" with some outside support for those with mental illness.
I would check with all of the city agencies that offer such services.
Unfortunately, since she is under the Public Guardian, if she says that she does not want contact with her family, they are not obligated to tell you anything. I would go the Public Guardian's office (not phone - but go) and talk to them. If she has disappeared, since the PG's office is legally bound to her, and responsible for her welfare, the police would be legally bound to let them know. And I think you will learn alot by going to the PG's office, if you possibly can.
PS - Public Guardians do not handle the money of a client. The Public Trustee does. So she would have both - A public guardian for her care and generally well being. A public trustee who would handle her money for her -
You might also contact the Public Trustee's office as well.
God Bless you, and while the task of locating her may seem daunting - the answer is out there somewhere.