First, finding life insurance for someone age 75 may be difficult, due to age, health, and life expectancy. In addition, the cost of life insurance for someone age 75 or over will be quite high.
However, some insurers may offer a smaller amount of life insurance for a higher premium.
That's why people buy life insurance when they are young and healthy, so it's affordable, and they have the life insurance coverage when they need it most.
One option may be to save the money ($120 per month) in a savings account set aside for your grandma's final expenses, or try to get a guaranteed issue life insurance plan which offers a graded benefit the first 2 years. That means she won't have full life insurance coverage until she is insured under the policy for at least 2 years.
In addition, there are guaranteed issue life insurance plans available for people ages 45 to 85 with no exams and no health questions asked.
Here's a resource for life insurance for people over 70 to help you get started.