A person can create a Power of Attorney and a Will without an attorney, but only for himself or herself. A non-attorney cannot create these documents for another person. Forms from software and/or the internet are notoriously unreliable in how they are drafted, and those sources rarely provide the necessary instructions or counseling needed to create documents that are truly valid or effective. You are very likely to get a "good feeling" result rather than an estate plan that actually meets your mother's needs. You need to go see an attorney. These documents are nowhere near as expensive as it will be to hire an attorney later to fix the mess.
This advice is for general purposes only and does not establish an attorney-client relationship. Your situation is complex, and nothing you are going to learn online can possible address your needs sufficiently. You should seek counsel from a licensed attorney in your area before you take any actions.
You can do it--it wouldn't be prudent. There are basic rules as to who can be a witness; mess those rules up and the witness may be invalid. Similarly, there are basic rules concerning wills and associated documents--software doesn't always cover the rules for each state, nor necessary supporting documents. Get an attorney and save the heartache.
You might ask yourself whether your will sleep well after DYI not knowing whether you did it correctly. The previous two lawyers gave you good advice.
These comments do not constitute legal advice. They are general comments on the circumstances presented, and may not be applicable to your situation. For legal advice on which you may rely consult your own lawyer.