If you are a home user (i.e., you are not on a big network where you have no control over the other computers), then use any good default/deny solution, and it will protect you from ransomware and everything else.
MT favorites are: Voodooshield, and Comodo Firewall with @cruelsister settings.
Both are good.
There are standalone apps specifically for ransomware protection, but they are less effective.
Kaspersky Anti-Ransomware against Ransomware for free.
or VoodoShield free on Smart mode, and don't allow things you don't know what is.
Paid: Kaspersky Internet Security, Emsisoft Anti-Malware, Bitdefender Internet Security, FSecure SAFE.
Combining KAR with any of your AV choice is good too.