I'm new to making cupcakes and in the past it seems the times I have made buttercream the cupcakes don't fare well the next day as the frosting has hardened. 

I haven't had this problem with my cream cheese frosting! It seems fine the next day!

I know ideally I should frost the day of but I'm out of town and working in my MIL's kitchen so  I had no choice. I'm thinking I should've just made the cream cheese frosting. Should I just make a second batch to hedge my bets? Extra cupcakes never hurt I suppose.

Don't use a crusting buttercream.  Like your cream cheese frosting there are many that don't crust.

An SMBC (Swiss Meringue Buttercream) or IMBC (Italian Meringue Buttercream) are perfect for this. 

If you prefer American-style buttercreams, try searching "non-crusting buttercream".

because cream cheese frosting needs to kept refrigerated for safety which would dry out the cupcakes 

charmdesign, there's a recent thread called 'red velvet' that has a discussion about alternate cream cheese icing check it out for a really different way to get a safe tangy sweet good icing that doesn't require refrigeration

http://www.cakecentral.com/forum/t/828628/red-velvet

Ah! I just made a second batch with cream cheese frosting before reading these responses- am I safe to serve the EITHER?

Rookie errors GAH!

I should add this is just for a family Easter dinner but there will be 30 people or so.

I have no idea what I was thinking.

he buttercream recipe only had a T. Of heavy cream, FWIW. 

Can I salvage the situation?

cream cheese has a four hour window to be out of temperature -- the cream is no worries in this application -- so if you keep your cakes sealed in plastic in the fridge you should be ok but just watch your time