You won't like the answer were going to give you, but it is the best medicine (remember the expressions in the Little Rascals movies when they were forced to take Castor Oil?). You need to hire a lawyer. Anyone can fill in a blank will form but the odds of that really doing what mom needs are usually pretty slim. If mom owns no property she might not really need a will. How are mom's assets owned (what does she have if she has no property?). If she has bank and brokerage accounts only, and those are joint with her children (are you the only one?) then there may be no need for a will as those assets would pass automatically on her death by operation of law.

What your mom should have is a plan. That might entail Medicaid/elder law planning to safeguard assets. She should have a durable power of attorney, HIPAA release to permit access to medical records, a living will and health proxy to help with medical decision making, etc. Are there any family issues that may arise (if you have siblings that is a good possibility). How should personal property like jewelry, art, furniture, etc. be dealt with? That may be simple in your case, but too often the simple fill in the blank will forms just don't do it. Be careful and take care of mom. A consult with an estate or elder law attorney should be step 1.