Tower Controller reported the TRACON Controller turned an aircraft below the minimum vectoring altitude to clear a conflict.

Narrative

I departed Aircraft X on the SID; runway heading. I then coordinated Aircraft Y on a 002 heading; with the radar handoff position; which they approved. I had already switched Aircraft X to departure; they appeared to be having no issues and were climbing on the SID as they should have. I issued Aircraft Y his departure clearance with the heading and also stopped their initial altitude to 7000 ft.; due to a point-out which I approved. Aircraft Y departed and as they got airborne I again gave them their 002 heading to insure I had diverging courses with them and Aircraft X 4 miles on the upwind. I observed the turn and switched Aircraft Y in a timely manner. It looked fine out the window. On radar it took a sweep or two to show Aircraft Y's turn and they had an alarm go off with Aircraft X. Out the window everything looked okay; but then I did key into Person A's position and heard them turn the Aircraft Y below the MVA and amend their altitude again; which led me to believe; Person A wasn't sure who was supposed to be on the 002 heading and that I had already amended the Aircraft Y altitude; knowing that they would eventually be going eastbound and conflict with the point-out. I feel if Person A and Person B were coordinating with each other better that Person A would have known that Aircraft X was eventually going to go on the initial fix on their flight plan; a 342 heading; and would have been better to turn them to the west since they were at 4100 ft. instead of turning Aircraft Y below the MVA who was still climbing out off the departure end.