Is the passage of dialogue written correctly or incorrectly?

Then he added, "I have a new idea for a tree house." "Will it cost a lot?" his mother asked. "I think we can do it for free," Vernon replied.

A.
correctly

B.
incorrectly

My last vacation, which took place in the summer of 2019, I decided to travel with my family to the state of Florida to visit the Disney and Universal theme parks, and later the beaches of Miami Beach.

The trip began in Orlando, where we visited the Magic Kingdom, Disney's Hollywood Studios, Epcot and Animal Kingdom parks, belonging to Walt Disney World; and then the parks of Universal Studios and Universal Islands of Adventure. In all these places, we haf great days of fun and adventure, enjoying new attractions and the magic that these places offer to those who visit them.

Finally, after 8 days in Orlando, and after visiting some shopping malls and the city center with its imposing Lake Eola, we headed towards South Florida. After 4 hours by car, we reached the imposing city of Miami, where we could see the American Airlines Arena and Bayfront Park as soon as we arrived. There we spent 7 days of relaxation, enjoying the beaches of South Beach and strolling on Ocean Drive at night.