I think you have to work through this one item at a time.
1/ There has been an accrual. Now an accrual is usually Dr Expenses (P&L) and Credit Accruals (Balance Sheet). The questions says that the figure has been correctly refelcted in the P&L, so it is just the Cr Accruals part that has been missed (and entered into Suspense). So to correct Cr Accruals and Dr Suspense.
2/ As above the figure has been correctly refelcted in the P&L so it is just the Prepayment account (Balance sheet) that has to be corrected. A prepayment would be a debit entry so to correct Dr Prepayments and Cr Suspense.
3/ This hasn't affected the supense account as the bookkeeper has made entries (albeit incorrect).
So the last adustment must relate to the sale of the asset.
Cr 1508 b/f
Cr 217 Prepayment adj
Dr 475 Accrual adj
Balance Cr 1250
So this is the amount corrected (and clearing suspense account).....Dr Suspense, Cr Gain on disposal (P&L).
It is always a good idea to think about what should have happend and always think about the double entry the Dr's and Cr's or Dr = +ve; Cr = -ve.
As for your second post.....yes, the day book comments are irrelevant to the suspense account entries.
