Is it safe to let to a retired elderly?

Would it be safe to let to a retired old lady who offers to pay a 6 months upfront? I asked my letting agent if it’s better to request the old lady to provide a guarantor as the lady has no longer had any more income. But the agent said that getting 6 months upfront and having a 6 months break clause in the contract could be secured enough. Having a guarantor is in fact not practical. What do you think?

What on earth would you want someone with no income?

She has no state pension?