Command:

./ffmpeg -i 5BCD2B50-E87C-4549-865A-CCC7B1DB96DA.mp3 \
-i 7D1393B3-5B8C-4D5B-866E-141454E4DDB2.mp3 \
-filter_complex " \
[0:a] atrim=26:60 [trimmed0]; \
[trimmed0] afade=t=in:st=0:d=7 [fadedin0]; \
[fadedin0] afade=t=out:st=50:d=9 [fadedout0]; \
[1:a] atrim=0:29 [trimmed1]; \
[trimmed1] afade=t=out:st=24:d=5[fadedout1]; \
aevalsrc=0:d=26[paddedoutput1]; \
[paddedoutput1][fadedout1] concat=n=2:v=0:a=1 [padded1]; \
[fadedout0][padded1] amix=inputs=2" -y out.wav




Output:
rohan@rohan-vbox:~/test_folder$ ./run.sh
ffmpeg version N-53555-g6b7ce0e-static http://johnvansickle.com/ffmpeg/  Copyright (c) 2000-2016 the FFmpeg developers
  built with gcc 5.3.1 (Debian 5.3.1-11) 20160307
  configuration: --enable-gpl --enable-version3 --disable-shared --disable-debug --enable-runtime-cpudetect --enable-libmp3lame --enable-libx264 --enable-libx265 --enable-libwebp --enable-libspeex --enable-libvorbis --enable-libvpx --enable-libfreetype --enable-fontconfig --enable-libxvid --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora --enable-libvo-amrwbenc --enable-gray --enable-libopenjpeg --enable-libopus --enable-libass --enable-gnutls --enable-libvidstab --enable-libsoxr --enable-frei0r --enable-libfribidi --disable-indev=sndio --disable-outdev=sndio --enable-librtmp --enable-libmfx --cc=gcc
  libavutil      55. 19.100 / 55. 19.100
  libavcodec     57. 28.103 / 57. 28.103
  libavformat    57. 28.102 / 57. 28.102
  libavdevice    57.  0.101 / 57.  0.101
  libavfilter     6. 39.102 /  6. 39.102
  libswscale      4.  0.100 /  4.  0.100
  libswresample   2.  0.101 /  2.  0.101
  libpostproc    54.  0.100 / 54.  0.100
[mp3 @ 0x4fd22a0] Estimating duration from bitrate, this may be inaccurate
Input #0, mp3, from '5BCD2B50-E87C-4549-865A-CCC7B1DB96DA.mp3':
  Metadata:
    artist          : FamilyJules7x
    TCM             : Danny Baranowsky
    album           : PC Covers
    genre           : Video Game Music
    date            : 2012
  Duration: 00:07:25.60, start: 0.000000, bitrate: 328 kb/s
    Stream #0:0: Audio: mp3, 44100 Hz, stereo, s16p, 320 kb/s
    Stream #0:1: Video: png, rgb24(pc), 720x720 [SAR 2835:2835 DAR 1:1], 90k tbr, 90k tbn, 90k tbc
    Metadata:
      comment         : Other
Input #1, mp3, from '7D1393B3-5B8C-4D5B-866E-141454E4DDB2.mp3':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2mp41
    encoder         : Lavf57.28.100
  Duration: 00:02:14.14, start: 0.025057, bitrate: 139 kb/s
    Stream #1:0: Audio: mp3, 44100 Hz, stereo, s16p, 139 kb/s
    Metadata:
      encoder         : Lavc57.28
Output #0, wav, to 'out.wav':
  Metadata:
    IART            : FamilyJules7x
    TCM             : Danny Baranowsky
    IPRD            : PC Covers
    IGNR            : Video Game Music
    ICRD            : 2012
    ISFT            : Lavf57.28.102
    Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, stereo, s16, 1411 kb/s (default)
    Metadata:
      encoder         : Lavc57.28.103 pcm_s16le
Stream mapping:
  Stream #0:0 (mp3) -> atrim
  Stream #1:0 (mp3) -> atrim
  amix -> Stream #0:0 (pcm_s16le)
Press [q] to stop, [?] for help
Error while filtering: Cannot allocate memory
size=    5857kB time=00:01:00.00 bitrate= 799.7kbits/s speed= 307x
video:0kB audio:5857kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.002634%
rohan@rohan-vbox:~/test_folder$ free -m
             total       used       free     shared    buffers     cached
Mem:          2000       1764        236         23         51        647
-/+ buffers/cache:       1064        936
Swap:         2045        115       1930