If you are looking for final expense life insurance coverage for them to help pay for their funeral and burial costs there are life insurance websites that cater to that type of policy.
As long as your parents are aware you are buying life insurance on them, give you permission, and sign the application for coverage, then any life insurance company may allow you to take out a life insurance policy on your parents.
To take out life insurance on another person you must have and insurable interest in that person, such as, family members, spouses, relatives, business partners.
An adult child has an insurable interest in his or her parents, so you could buy life insurance on your parent, or both parents.
Here's how to buy life insurance on your parents.