Mother Love is self-explanatory - there is nothing to wonder about :-)
In the youtube video, the maker of the video shows the picture of Freddie's mother when the word "Mama" is sung. In my humble opinion, I think the "woman" who gave him sweet mother love might be Mary Austin and therefore she would be the "mama" in the song and not his mother :-)
I learned in a psychology lecture once that the last words of dying soldiers on the battlefield were, overwhelmingly, "mother" or "mom". Freddie was getting very close to the end, and there must have been fear and the drive to seek love and comfort and perhaps even protection at a very fundamental level. I've always thought that maybe that's what 'Mother Love' was rooted in.
I think it was cowritten. But that's not really important I don't think. The Show Must Go On was written/cowritten by Brian as well, and that was pretty clearly filtered through an experience Freddie was living.
It's all so scary. There's tons of people who claim Freddie was in it just for the money, but with some of those last songs, you can tell he did it clearly for his love of music. His enjoyment and happiness.