Can a surviving spouse (in Ontario, Canada) change the disposition of the remains of a deceased spouse if other clearly stated wishes were formalized in a will? (ie deceased wishes were to be buried, surviving spouse wishes to keep remains in residence).

She can challenge the will, but she can't just arbitrarily ignore the provisions of the will.

On the other hand, someone will have to file legal action to force her to adhere to the terms of the will.

By the way, I'm assuming he was or will be cremated. There are laws preventing someone from keeping remains of a deceased anywhere but a licensed cemetery.

Are there other family members who would contest her during this.

But if this was his wishes why would they want to dishonor his memory by doing something he did not want done, why not merely a memorial of some sort in the home.