We need non-determinism in PDA to accept this.
After pushing all the a's, create two instances where
- The first instance pops one a for one b
- The second instance pops one a for two b's
Or create two instances from the start state where
- The first instance pushes one a for one a and pops one a for one b
- The second instance pushes two a's for one a and pops one a for one b.
Hence, Option B