Need advice about Psychiatric help

My mom has ran away from the house for more than three times now. She left saying that she is going to a nearby shop or someplace for few minutes but gets lost randomly.And once the person who last met her once told that she was fine and gave the sane reason that she was going to a nearby place as she told us while leaving home.. So it is sort of random rather than a planned runaways which she too feels sorry about(although it shouldn't be). And every time she had called back home by the end of day.. So it lasts maximum a day.. Is it a fugue disorder? She remembers and tells some places where she had gone but no one probes much further because it may worry her more..
She initially battled cancer and was finally cured, but this made her depressive and at times she gets random episodes in the morning usually where it looks like she is not the same person- same as an individual and identity but very pessimistic, guilty, crying, sad and begging and sometimes even trying for death. The frequency of these went down very much compared to past year. But the only thing that makes her come out of this is a sleeping tablet and after she wakes up she realizes that she had disturbed us by all this.. So I am worried about any new sort of addiction that only a medicine is able to calm her back..
So should this be a case where psychiatric help is needed? My main concern is that what if the drugs do further damage? And by now I should all my trust on her and not allow her to go out alone, but how do I explain it to her when she's "normal"?
I want to know what medical help is given, basically how can it help to prevent something as random as this?

How long gas she been cancer free or stopped her treatment? Did she have IV chemo, etc? Chemo can wreak havoc with the brain and "chemo brain" is real and lasts for years after treatment. This can explain her getting lost. If she remembers, where she went, it's not a fugue episode. You may want to start with her primary doctor or Oncologist. The depression certainly warrants psychiatric help, but therapy or a psychiatrist that works with cancer patients is needed.

Hope that tells,
Kali