OP,
FWIW I don't think you are being at all unreasonable. I think the way you phrased the original question doesn't represent the reality of the situation. Presumably your mum is just like this, it's not a new thing which has begun with the birth of your daughter?
This is particularly upsetting, and such a fraught issue, because your DD is very young. 7 months is no time to get over something so profoundly affecting. While many posters have invited you, in rather strident terms, to acquire some perspective, they seem to have forgotten the fact that instead of supporting you in getting over the upset of a traumatic birth, which is important not only for you, but for your DD, your mother seems intent on upsetting you.
I would like to suggest this - when you feel calm and strong, you tell your mother how you feel - not in a passive-aggressive "are you happy I almost died" way, because this gives her an in to say you are being over-emotional, unreasonable - just state it calmly. Tell her that you know she loves the photograph, and you understand why, but ask her to remove it to somewhere you won't have to see it, as an act of consideration. Explain that it hurts you. Do it calmly, don't make threats or give ultimatums, just see what happens.
If she won't/doesn't do as you respectfully ask, consider carefully what she will be like as a grandparent, if this is her parenting style. Your DD is yours and your husband's responsibility, and your bond, your happiness with her and in her, and that of any future children, is more important than narcissistic power-play. But ignoring this sort of thing doesn't make it go away, and I don't think it's you who needs perspective. Perhaps you are more sensitive than usual, but with good reason.
Obviously, goes without saying, this is just my opinion, but I do speak from (a little) experience.
Congratulations!