How can I help my 85 year old dad who doesn't want to get up?

My 3 brothers and I are trying to care for our Dad. We lost our mom this past July. He is, I think depressed from her passing. He doesn't want to eat as he used to. Doesn't want to get up. His health was ok. Needed to put on weight. One brother is his primary caregiver. We have aides assisting and it's helping a bit. Any suggestions to help him. I m calling Dr tomorrow to ask about anti-depression med.

thank you.