All the Oscar winners in most of the categories certainly deserved it in that I cannot think of any performance better than them or one that I could put ahead of them. And this is not belittling the other nominations.
Dallas Buyers Club is a fantastically acted movie with all the lead actors (Matthew McConaughey, Jared Leto and Jennifer Garner) who bring a sense of normalcy and general life to their characters and situation. This helps in moving audiences and waking them up to the effects of AIDS and importance of medical treatment (especially in the early days). Both Leto and Matthew were deserving winners alongside the Best Film won by 12 Years A Slave and Best Actress and Best Supporting Actress going to Cate Blanchett (amazing as usual) for her role in Blue Jasmine and Lupita Nyongo for 12 Years a Slave respectively.
Overall, a fine fine year for movies!!