Benefit rules for property owners

Hello guys
My friend is a career girl, bought her own home and then a year or so in started to suffer from severe depression and turned up one night with a suitcase asking if she could stay.
a couple of years on and she is still here but finally started to rent her house out about a year ago or so after leaving it just empty and costing money for a year.
Her depression got quite bad seven months ago and she was signed off from work by her Dr - she has been dismissed now due to illness and in my opinion needs a bit more time yet to sort herself out before going back into employment - I am sure her dr will agree.

Now how does she stand benefits wise, she has never claimed anything before and doesnt understand the system and neither do I to be honest.
As she owns a house and has tennants in there will that money be taken into account (I would assume it would be) though also she has to pay a mortgage from that money so does that get taken into account too.

It would seem harsh that she would have to kick out her tennants and sell the house but is that the only route ?

I am not sure what to advise her with as I havent really been along the benefit route and know nowt about being dimissed due to illness etc.

any ideas guys ?