Your question is a bit confusing since it was not Mrs. Dubose's house that burned down; it was Miss Maudie Atkinson's. Atticus has little to say to Maudie on the night of the fire. After saving Maudie's oak rocking chair and carrying the possession "she valued most" to safety, Atticus stood beside Maudie as they watched the house burn and finally collapse. But Scout's narrative doesn't mention Atticus having a conversation with her. The next morning, Atticus related to Maudie the story about Boo Radley placing a blanket on Scout's shoulders, and Maudie mentions it to the children, assuring Scout that
"I'd've had sense enough to turn around, too." (Chapter 8)
Atticus always treated Mrs. Dubose with kindness, and he spoke to her in a friendly manner whenever he saw her.
... Atticus would sweep off his hat, wave gallantly to her and say, "Good evening, Mrs. Dubose! You look pretty as a picture this evening."
I never heard Atticus say like a picture of what. (Chapter 11)
After Mrs. Dubose's death, her house stood
... empty and shuttered, her camellias grown up in weeds and johnson grass. (Chapter 15)