My mother commited suicide when I was 12 and my sister was 10.  We had some pretty good neighbors at the time.

I doubt the kids will talk to you about it - they are probably way too young - don't ask them questions - but I guess if they do talk about it listen to them.  If thier mother works out - maybe offer for them to be dropped off at you home after school until she gets home from work. Assuming you or your wife will be ther anyway.  

Thier mother will definetly need help.

Those kids will need help in the future -  (depression, higher incidents of suicide (the idea is in thier head).

Hopefully you were close to the family before this - so if you really want to help they will be comfortable with you.  Good luck - what you are doing is a big commitment but the kids will remember.