"Her main goal is to provide security for her children by purchasing a home in the Toronto suburb where she lives."

If she is hoping to buy a home soon, the best place for the money is in a savings account.

If she may buy a home in the medium term, she could need the money all at once, so a ladder of non-cashable GICs is the worse thing she could have. Putting the almost-$300K into something like Mawer Balanced Fund would be preferable.