Python script developed by GRACE Science team converts the JPL GRACE Mascon file from netCDF4 to GeoTIFF format. The most current Mascon dataset can be found and downloaded from https://doi.org/10.5067/TEMSC-3JC62. This script decomposes the multi-year monthly Mascon netCDF file into single GeoTIFF files for each month.
You can download the software from https://github.com/podaac/GRACE. Feel free to ask any questions.