Can I know whether cisco WS-C2950C-24 support this transceiver, "GLC-SX-MM"?
On 2950 what you have is fixed 100base-FX interface and you can not install any other GBIC/SFP over here.
The only option you have is to have a 100base-FX interface on the 2960 switch and connect it to the 2950 100base-FX interface.
WS-C2960-24TC-L switch supports following 100base FX SFPs -
100base FX uses MMF. Look for the cable specification here -
Since 2950 switch which you have can not accomodate andditional GBIC you won't be able to use 1000 base-SX connectivity, you'll have to go for 100base-FX connectivity only.