Amounts paid as a bond on the hire of a hall, need to be included as a part of the event report, rather than as a non-event expense (or income when returned). This allows you to see whether the steward has fulfilled their responsibility as the representative (and therefore responsible person) of your group, as the hirer of the hall.
As bonds are generally paid before the event, as a part of the deposit on the hall, any bonds paid should be recorded in the expenditure section of the event report. The return of the bond can either be put into the income section or as a negative value in the expenditure section.
When reconciling a bond in Xero, you should allocate the bond to the “Cash Advances and Floats” account for your group - see the Xero Procedure Manual relevant section for more information on how to do this (noting that it is incomplete as of this writing - feel free to ask the list or the Exchequer for help if needed). When the bond is paid back this amount can also be reconciled against the same account, effectively 'zeroing out' the funds paid. As such, once all funds issues are received back, this account should have $0 in it.
A similar procedure can be used for cash advances for events and other purchases.