Replace/Renovate my mothers house

When my father left us for another women. My mom is the only one who makes an effort for me and my brother and sister. She even sold her house so that she can support us. Now we are living in that house on the photo. I want to give her a much better house. Maybe just to replace the house she sell for us. Im not asking for a lot. Just want to replace the roof and walls of that house. Thank you so much!