Trying to retrieve several user Ids and assign them to variables of Id type - but I am generally curious as to the best approach here - so I'm looking for opinions.  Thanks in advance!

In my view C) works but only if the SOQL returns records, otherwise you get a 'now rows returned' error.  A)  A works but again will return a "list out of bounds error if the SOQL returns 0 records  B) seems the best to me because if there is no key it simply returns null...but I'd like to hear your opinions.

So, which approach is the more efficient - which one is the best practice below, A, B or C (or Other) - is B the best? 
A)
list<User> jnldGenericId = [SELECT Id FROM User WHERE Name = '1' LIMIT 1];
list<User> rbdGenericId = [SELECT Id FROM User WHERE Name = '2' LIMIT 1];
list<User> imgGenericId = [SELECT Id FROM User WHERE Name = '3' LIMIT 1];
list<User> cclGenericId = [SELECT Id FROM User WHERE Name = '4' LIMIT 1];

Id Owner1 = rbdGenericId[0].Id;
Id Owner2 = imgGenericId[0].Id;
Id Owner3 = cclGenericId[0].Id;
Id Owner4 = jnldGenericId[0].Id;

OR

B)
map<String, Id> userNameIdMap = new map<String, Id>();

for(user u : [SELECT Id FROM User WHERE Name = '1' OR Name = '2' OR  Name = '3' OR Name = '4'])
{
    userNameIdMap.put(u.Name, u.Id);
}

Id Owner1 = userNameIdMap.get('1');
Id Owner2= userNameIdMap.get('2');
Id Owner3 = userNameIdMap.get('3');
Id Owner4= userNameIdMap.get('4');

OR

C)
Id Owner1= [SELECT Id FROM User WHERE Name = '1' LIMIT 1].Id;
Id Owner2 = [SELECT Id FROM User WHERE Name = '2' LIMIT 1].Id;
Id Owner3 = [SELECT Id FROM User WHERE Name = '3' LIMIT 1].Id;
Id Owner4 = [SELECT Id FROM User WHERE Name = '4' LIMIT 1].Id;