ANSWER: Fundraising is the raising of money for a cause, which in this case seems to be for a worthy effort. From your Email, you also stated that some church members rejected raising money on church grounds based upon some Bible verses in Mark 11. These verses discussed Jesus chasing out the "moneychangers" and those who sold pigeons and other goods out of Jerusalem's temple.
The changing of money was a needed service for the temple. Any currency that would be used at the temple (for example, as an offering) had to be exchanged for special coinage. Moneychangers made their money by charging a fee (a fee THEY set) for exchanging currency. This business could be very lucrative, in part, because it was so easy to cheat people.
What Jesus did in Mark 11 has little in common with trying to help the needy using church property. What Jesus did occurred at Jerusalem's temple, which was considered the "house of God" and a house of prayer for all the nations. He was not angry with those in the temple area because they were earning a living, which every person needs to do. He was mad, and understandably so, because these businesses were taking advantage of people! They were making a dishonest gain by cheating and robbing people for something (like temple money or animals for sacrifices), they had to have in order to worship at the temple. This is why he said these businesses had turned the temple into a den of thieves (or robbers) in verse 17.
Fundraising, whether it is on the grounds of where the church meets or in its buildings, is different from what Jesus condemned in Mark 11. The word "church" in the New Testament is the Greek word ekklesia (Strong's Concordance Number #G1577). It means a community of converted members (called-out ones) on earth or saints in heaven. As such, it is NOT used to refer to a building, group of buildings, areas, etc. used by Christians for worship. The "church," when referencing Christians as individuals who meet together, is indeed holy (Colossians 3:12, etc.). A building or plot of land USED by Christians is not, of itself, HOLY. This is in contrast to God's temple in Jerusalem, which was not only dedicated to God but the building itself was set apart as holy directly by HIM.
Additionally, Jesus condemned those at the temple because they were robbing or stealing from others for their OWN benefit. Raising funds on church owned property by selling stuff (usually donated) at a reasonable fee and using the proceeds for OTHERS who have legitimate needs is a far cry from robbery for godless gain.
It is commendable that elderly people, on limited retirement income, still want to do their share in serving the Ekklesia or church. Fundraising activities such as hosting a paid meal open to the public, or selling soda, chips, cakes, cookies, snacks and so on are an excellent way for them to be able to serve and do their part in contributing to the benefit of other believers in the group. The God of the Bible does not condemn activities like this.