Yes, provided she has one continuous qualifying year with the Canadian company in the last three, both companies are actively doing business, and the U.S. role is primarily executive or managerial in fact. Ownership does not bar the petition but does invite closer review.
Ownership is allowed; a title is not enough
Nothing in the L-1 rules prevents a company owner from being the transferee. The petitioner is the U.S. subsidiary, and she can be its intended executive even though she controls the parent.
What USCIS will examine is whether the arrangement looks like an actual employment relationship and whether the U.S. duties are primarily executive. For the first point, the Canadian corporation must have treated her as an employee, with payroll, deductions and a board appointment, for at least one continuous year within the three years before filing.
For the second, the petition has to describe a role in which she directs the organization rather than performs its services. A four-person subsidiary can support an executive if the technicians are supervised by a lead and she is freed to set direction, negotiate contracts and manage finances. If the honest description is that she will be the best technician on site, the classification is wrong, and a different plan is needed.