Yes. If you have an Insurable Interest in someone, you may be able to buy a life insurance or burial insurance policy on that person.
Since she is your mother-in-law. and you and your spouse may be responsible for paying for your mother-in-law's burial upon her death, you may be able to buy a burial policy for her.
Burial plans provide the funds needed to cover the cost of someone's burial expenses, and usually provide up to $20,000 of insurance protection.
Here's how to buy life insurance for your mother in law to cover burial expenses.