I was playing a game last night with my players and we have 2 rangers.

Both rangers are 2024 Rangers, 1 is a FTD Drakewarden and the other is a TCE Swarmkeeper. 
Both players have Sharpshooter but the drake warden is using 2014 (-5 Attack, +10 Damage) and the other is using the new 2024 rule version.

My question is: Are players meant to take the version of the feat for their version of the class or
1) Can it be mixed and matched
2) Is it the DMs choice
3) Do players using 2024 rules have to use the 2024 version of feats?

The general idea is that if you're playing under 2024 rules, you should not be using the old version of anything that has an updated version in the 2024 rules. That includes classes, subclasses, species, spells, items, feats, everything. It's okay to use older things that haven't been updated (which includes both of those subclasses) but in some cases some adjustment will be necessary.

Obviously it's always up to the DM to make the final call, but this approach is intended to keep things balanced and make sure that some player characters don't feel weaker compared to others.

I don’t know about “have to” but it’s probably better if they do use the updated version. 

And in this case, I’d say the group (or the DM) needs to choose one or the other. I doubt it would be game-breaking to have them both. But as a DM it would be a real pain to have to try and remember who can do what and have to make rulings based on 2 versions of the same feat. Then you can get to situations where Bob can do a thing, but Sally can’t even though they have the same feat. It’s just confusing. 

My understanding was that the 2024 rules superceded the 2014 rules if both have the same feat or spell. If you're using the 2024 rules and the feature was reprinted in 2024 you use the 2024 not the 2014. If you had the option to pick which version every spellcaster would be taking the 2014 counterspell over the 2024.

When you play D&D with the 2024 Player’s Handbook, it replaces all rules, classes, subclasses, spells, feats, equipment, species, and backgrounds in the 2014 version of the book. There are a few exceptions; the following options don’t appear in the 2024 book and are still usable from 2014: [...]

Any subclass, spell, or feat from Xanathar’s Guide to Everything or Tasha’s Cauldron of Everything that appears in this book replaces the version that appears in the Everything book.

This thread is useful too: Rules Summary: Using 2014 character options on 2024 characters - General Discussion