A lot of places won't lend to pensioners, however there are still a few that will. It really depends on your mothers income, the lender will need to be satisfied that she can afford the repayments.
The minimum amount for a secured loan is usually more than �7K though.
She could get a 'lifetime' mortgage, where no repayments are made. The capital and interest are repaid upon death when the house is sold. I believe they can be very expensive though.
Here is one that NatWest do. Other lenders probably do the same type of thing.