Something that I strongly recommend you not do, even if it's something that comes natural to you. Do not see this individual as a problem to solve. Depression and suicidal ideation, if they exist for this person, will likely be a part of the person for the remainder of their life. You cannot fix it.

There are several things, however, that can help. Be sure that the individual knows that they have your love and support unconditionally. Make sure that they know you see them as a person, not as a symptom. If your children are really fond of them, posts, pictures, updates, whatever from them can be very helpful. Just knowing that someone as unbiased as a child looks up to them, I think, can be huge. Also, be sure to allow them enough space to respond as they are able to. I had times when I couldn't speak or respond to anyone in any way, when just getting out of bed was impossible. Other times, a simple response to others made my day. (I was never suicidal, though ideation was present.)

Suicide prevention hotlines might be your best first step if you think it has progressed to ideation. They should be well versed in some good resources. Bluebloodcoug may be right with the local police department. I don't know.