How much should I deduct from tenants security deposit?

[Sam Sav]

Hi everyone. Just thought I'd ask to get more opinions on what's a fair amount to deduct from my tenants security deposit? I've had them in for almost a year now. April 15th is when they'll be moving out and I will be moving in as I am getting married in May of this year. The house is a 1,200 sq ft split level house with 3br/2bath. I can't complain about the tenants they were pretty great. Always paid on time and are pretty clean. Besides the fact that they have a lot of furniture and unnecessary clutter from what I saw. The time they've been here I had to replace the furnace because it kept breaking down and there was a big flood in the neighborhood last summer that caused a flood of about 5 inches in the basement. I had all new appliances in there besides a used washer and dryer. According to them the dryer stopped working after the flood but they never told me that until after a month of the flood. But I went ahead and replaced it with another used one. 

The only thing I've seen broken is the handrail going down the stairs. It will need some plastering and painting.

So I'm just kind of wondering how much out of the security deposit is it fair to deduct. Considering  the handrail and I guess repainting the whole house since they have a lot of clutter that I'm sure scratched up the walls