Step1
Don't go running to the phone, calling the home builders just yet!
Instead, approach your son-in-law in a non-threatening manner asking if you could talk. Be sure that you do this in a neutral location, away from home, where you will not be interrupted.
Step2
Bring the home remodeling to his attention gently. Make observations and statements like, "I've noticed this is not completed, I was wondering how I could help make this happen."
"I feel that this could be accomplished by doing x, y and z."
"Your friend or a family member is willing to help and we could watch the kids."
Make sure he knows your concerns such as family safety, money, furniture, structure, living conditions, quality of life, etc. Always preface your concerns with "I feel that..."
Step3
Be as helpful as possible, reinforce any dialog with
"I understand ... (how you feel, it is difficult, etc). This will diffuse tensions and help him listen to you.
Step4
Try to keep your daughter out of it, if possible. Keep the focus on the house project. If he tries to go off the subject, gently refocus him.
Keep it simple and direct and easy for him to complete this logistically. Meaning, take care of the child care, errands, materials, supplies, payments, money, food, materials, or helpers. Do not be afraid to remove any other barriers you can think of.
Step5
If he is not sure how to complete the project or does not feel qualified, search local ads for home builders who could either offer assistance or complete the work. Many will let you make payments. Be sure to interview the business owner and ask for references.
Step6
Do not let him leave the meeting without setting a definite date to either move forward with his help or to hire a local contractor by a set date. If possible, the holidays make excellent deadline material.