It depends on your needs quite a lot
It's not like you think about a core i5 and have a preselected idea of what is needed.
In case of RAM, If plan to play games just get 8GB it's good enough for any actual game. Going for 16GB will give you 1 or 2 FPS more so it's a waste of money
If your PC is dedicated to some heavier tasks such as rendering, after effects, streamming, intensive multitasking etc I'd recommend 16GB
being an i5 6500 almost any mobo works fine for what you look for
I would pick a B150 mobo, it's got 6 sata ports, which should be enough and sopport for up to 64gb of ram
The h170 chipset doesn't compensate the extra cost a lot
The motherboard is difficult to choose
You have to keep in mind things like how many drives are you going to be using, how much RAM will you ever install, if you will OC or not, if you will SLI or CF
etc.
If you don't upgrade your PC parts in years and just want to have a compatible motherboard get any H110 mobo. Actually, no matter how low-end they are, they're still LGA 1151 mobos they have a bunch of features that you won't even use
Bu you'd need to investigate a bit more about mobo features to find out what kind of mobo you're looking for