Hanson missed Tuesday's impressive win over league leaders Burton Albion due to illness, while Davies has been sidelined for City's last three games with a knee injury.
After struggling with a virus during the Burton victory, Kyel Reid is also now back to full fitness. Jamie Proctor is a slight doubt for the Doncaster fixture, however, due to a tight hamstring.
Parkinson said: "We've had a bit of that (illness) around the camp recently.
"Kyel missed yesterday's (Thursday) training but he was back in today (Friday). James was also back involved with today this morning.
"Steven Davies is ready. He has trained all week and he is available for selection."
Parkinson also revealed that City have agreed a deal with West Ham United to extend loanee midfielder Josh Cullen's stay at the Coral Windows Stadium.
Cullen's current deal with City is due to expire after Saturday's game with Doncaster but he will now remain with the Bantams until the end of the season.
Parkinson continued: "I had a good chat with Terry Westley (West Ham's Academy Coach) this week and Josh was keen to stay as well.
"He has come in and fitted in really well with the squad and we are pleased with his progress so far."
After dislocating shoulder at Bury last weekend, Rory McArdle will unfortunately remain on the sidelines for Saturday's Yorkshire derby.
The Bantams' reigning Player of the Year is due to have his left shoulder checked over again this Friday to give City a better idea of the damage caused.
Parkinson added: "Rory will see a specialist about his shoulder later today so we should know more then about the injury and how long exactly he will be out for."