Re: Finance/commerce (accounting) or Law/commerce (accounting), which has more 'scope
There aren't many employment opportunities in law? I don't think this is necessarily true, especially if you do well in the degree.
Law can lead to work in law firms, in-house, public policy, NGO's, government departments, tribunals, private practice.
Accounting/Finance = pretty much anything in business because the two are both useful majors.
Which has more scope?
That's a difficult question because it depends what you want to do. Law/Commerce(Accounting) would allow you to apply both to business roles as well as legal ones while Finance/Accounting would narrow you down solely to the business field. In the case you're leaning towards Law/Commerce but think one business major isn't sufficient for a career in business, keep in mind there's always postgraduate study (MBA, MManagement etc)
Which do employers value more?
I really don't know but if I were an employer my thoughts would be somewhere along the lines of: Law/Commerce(Accounting) - this person has both great analytical, verbal/written skills as well as quantitative knowledge applicable to the business environment. Finance/Accounting - this person has a strong interest in business especially crunching numbers.
In saying all this, maybe think about whether you're really interested and would consider a career in Law. Don't do it just for the sake of the degree because it is a lot of work and it's a professional degree that many confuse for a generalist one.